Question

Keliling persegi panjang = 140cm dan selisih panjang dan lebarnya 20cm.hitunglah panjangnya!

Answer 1

140 : 2 = 70
panjang = 25
lebar = 45

Answer 2

Diket :
K = 140 cm
p - l = 20 cm
p = 20 + l

Maka,
K = 2(p + l)
140 = 2(p + l)
70 = p + l

Masukkan p,
70 = p + l
70 = (20 + l) + l
70 = 20 + 2l
2l = 70 - 20
2l = 50
l = 50/2
l = 25 cm

Masukkan l,
70 = p + l
70 = p + 25
70 - 25 = p
p = 45 cm

Jadi, panjangnya adalah 45 cm