jwabanya apa tolong kasih tau butuh kepastuan

Keliling : 2p + 2l
2p + 2l = 40
2(12) + 2l = 40
2l = 40 - 24
2l = 16
l = 8 cm

Luas : p x l
8 x 12 = 96 cm persegi.

keliling = 2 (p+l)
40 = 2p + 2l
40 = 2 x 12 + 2l
40 = 24 + 2l
2l = 40-24
2l = 16
l = 8
maka
luas = p x l = 12 x 8 = 96

semoga membantu