Perbandingan panjang dan lebar suatu persegi panjang adalah 5 : 4, jika kelilingnya 144 cm, maka luasnya adalah...

K = 2 × (p + l)
144 = 2 × (p + l)
p + l = 144/2
p + l = 72 cm

p = 5/(5+4) × 72 = 5/9 × 72 = 40 cm
l = 4/(5 + 4) × 72 = 4/9 × 72 = 32 cm

L = p × l
= 40 × 32
= 1280 cm^2

jml.perbandingan kll = 2p + 2l
= 2(5) + 2(4)
= 18

perbandingan panjang = 5

panjang
= perb.panjang/jml.perb x kll persegi
= 5/18 x 144cm
= 40 cm

perbandingan lebar = 4

lebar
= perb.lebar/jml.perb x kll persegi
= 4/18 x 144cm
= 32 cm

Luas.persegi
= p x l
= 40cm x 32cm
= 1280 cm²

semoga membantu ya dekk:))))