tolong yaa ka pake cara

12:4 dan (2y+5):7
dikalikan silang
8y+20=84
8y=84-20
y= 64/8
=8

2y+5
2(8)+5=21

L= P×l
=12×21
=252 cm²

12x(2y+5)
=24y+60
24y=60
y=60/24
y=2.5
jadi 24y+60 = 24x(2.5)+60 =120

di cek lagi yaa