Pertandingan b panjang dan lebar suatu persegi panjang 3:2jika keliling 90cm tentukan luasnya

panjang = 3x
lebar = 2x
keliling = 2(p+l)
=2(3x+2x) = 90
2(5x) = 90/2
5x = 45
x = 9

panjang
= 3x = 3(9)
= 27

lebar
= 2x=2(9)
=18

luas = p x l
= 27 x 18
= 486 cm2