Mohon dibantu yakk..

p = panjang
l = lebar

p - 10 = (l - 10) + 20
p - 10 = (l - 10) + 20
p - 10 + 10 - 20 = l

p + 5 = 2 x (l + 5)
p + 5 = 2l + 10
p + 5 = 2 x (p - 10 + 10 - 20) + 10
p + 5 = 2 x (p - 20) + 10
p + 5 = 2p - 40 + 10
5 + 40 - 10 = 2p - p
35 = p
l = 35 - 20 = 15

Total panjang dan lebar:
= 35 + 15
= 50

Jawaban : E

Misal, panjang = p, lebar = l

p + 5 = 2 × (l + 5)
p + 5 = 2l + 10
p - 2l = 5

p - 10 = (l - 10) + 20
p - l = 20

Eleminasi kedua persamaan, didapatkan hasil l = 15 cm, p = 35 cm