I wanted to look up your stats, but it looks like this is an account you created to specifically play with him? I also wanted to look up his stats to see who he plays and the roles. Just to get an idea of what he plays, his trends, and habits. My guess is that you are a silver player, so you probably are not good enough to hard carry in a 4v5 and if you play with your friend it is probably a 4v5 every game.
First off, if you are not patient, don't play with him too much, because you will just be discouraging him from playing if you get agitated. This game needs new players.
If he is very new to the game, he will barely understand much about what he should be doing his abilities or the abilities of his opponents. He also may not understand terminology that you use, or he will have to sit and process it a moment.
You telling him to use a skill while you gank, he may be thinking "what is the name of the skill i should use what button is it" the entire time.
Then you die and it is too late, but the seconds it takes one to process information separates life and death in league.
You need to get in the mind set that "I will probably lose this game, no matter what" every time you play with him. And that you cannot count on him to do anything but die. That's it. It is just that simple. If you don't like losing every game, then don't play with him.
Accept that the game you are going into is figuratively a 4v5 even though he is a player. So once you have the mindset of accepting the loss you should be ok, if you can't get in that mindset you will just get progressively madder.
Right now, I have a buddy who is new to the game and every time I play with him he gets stomped and we lose at 25 minutes typically. I am not good enough to hard carry him, especially if the role he is learning is my main role (top). So, I only play with him to try new things and teach him some fundamentals.
When I first learned the game, it literally took me months 3 or 4 just to be decent at the game AND not feed horrendously. That didn't mean I didn't feed, that just meant that I didn't go 0-10 15 minutes into the game.
I also had 3 friends I knew in real life, all of varying skill from platinum, silver, diamond, providing me A TON of information to process EVERY game.
It is a lot to take in and most of it is hard to process until you have been playing a lot of games. I simply got better from playing and I would just focus on CS in games if I was feeding. I burdened my team but they understood that I sucked.
You can't get mad at people that are learning the game if you want them to continue playing, YOU CAN totally get upset at players that KNOW BETTER.
I have several bronze and low silver friends I will play normals with. They are good enough at the game to understand what I tell them to do and how I direct them. I understand that they will miss skillshots and die to better opponents, get caught, feed etc. Knowledge and experience does not translate to execution.
So, I don't get irritated when they miss skills, feed, or misplay. I only get irritated at them when they DELIBERATELY deter from what I directly tell them they should NOT do. What do I mean with that? When I tell our jungler "don't do the dragon they are all up and have vision of you doing it" and my friend proceeds to do dragon despite what I tell him and dies in the process because the enemy team rotates to him. That will get me mad in game.
Juxtapose to that, I will not get upset if I tell our mid laner "don't feed against yasuo" and they die 4 times at the 10 minute mark. But I will get irritated if I tell them to "give up the tower" and they continue to defend the tower.
You are playing with someone who lacks basic and fundamental comprehension of the game, meaning just because you tell him what to do, does not mean he can comprehend it, even if he has played for a bit.
My friends in bronze in silver are bad, but they understand and have enough understanding of the game to process and comprehend that information, your buddy does not.
Bot games will not help him, despite the popular belief in low Elo you can play against a few bots and pick up basic mechanics of a champion: you can't. You get better from playing mostly against real players.
I would tell you this, just have him focus ONLY on CS. Don't have him focus on ANYTHING else and tell him to pick a champion that he has fun with. He needs to have fun playing a champion so that he keeps playing that champion and improves.
The learning process will be months buddy, he can't just get decent after a few weeks of you directing him.
You also may want to ask him his MS in game and his FPS is he if reacting so late. I doubt this is the problem, but you should still consider technical issues just in case.
Edit: Also don't try to explain the meta too him. Let him try and fail. I took 
mid when I was learning the game and it wasn't until I was repeatedly poked out of lane that I understood that I can't take him mid.
