perbandingan persegi panjang p : l 3 : 2 keliling = 40 cm maka luasnya

misal :
p = 3a
l = 2a

K = p + p + l + l
40 = 3a + 3a + 2a + 2a
40 = 10a
a = 40/10 = 4
a = 4

p = 3a = 3(4) = 12
l = 2a = 2(4) = 8

L = p × l = 12 × 8 = 96cm2