Bantu dong pakai cara

Rata-rata Gabungan
Xgab=(Xp.P+Xw.W)/(P+W)
81(P+W)=(75P+90W)
81P-75P=90W-81W
6P=9W
P/W=9/6

P=9/(9+6)×25=(9/15)×25=3×5=15