keliling persegi panjang 40 cm,sedangkan panjang 12 cm.luas persegi panjang berapa ya... kalau bisa pakai cara...

K = 2p + 2l
40 = 2(12) + 2l
40 = 24 + 2l
2l = 40-24
2l = 16
l = 16/2 = 8 cm

L = p × l = 12 × 8 = 96 cm2

keliling 40 pnjg 12
lebar?
Lebar = (keliling - (2x Panjang)) : 2
= (40 - (2x12)) :2
= (40 - 24) :2
= 16 : 2
= 8 cm

Luas = pnjg x lebar
= 12 x 8
= 96 cm²