Pretty sure I gave my friend atleast half my LP when duo q'd

Okay so me and 3 other friends played a ranked game. Needless to say I carried hard. All of my friends got 13 lp and my one other friend took a wopping 38 lp. We all normally get 20 lp atleast but I got 13 that game and he got 38.

Ranks: Me (Gold 4) Friend 1 who got all the LP (Silver 2) Friend 2 (Silver 4) Friend 3 (Silver 4)

How did this happen??