tolong kerjain mana yg bisa aja ya dan pakai caranya

15. AP + PB = AB + BC = AC
16. AP - DP - CD + CB, bisa ditulis AP + PD = AD + DC = AC + CB = AB, AB = DC
17. BC + PD + DA + CP = BC + PA + CP = BP + PA = BA
18. BP - CD + PD = BP + PD = BD + DC = BC
19. -
20. -


maaf kalau salah, smeoga membantu :)