Diketahui keliling persegi panjang 94 cm, dengan ukuran panjang (5x + 2) cm dan kebar (2x +3) cm. Lebar dan panjanh persegi panjang tersebut adalah

k = 2 × (5x + 2)+(2x + 3)
94 = 2 × (7x + 5)
7x + 5 = 94 ÷ 2
7x = 47 - 5
x = 42 ÷ 7
x = 6

lebar = 2x + 3 = 2(6) + 3 = 15
panjang = 5x + 2 = 5(6) + 2 = 32

K persegi panjang
= 2 X ( p + l )
= 2 X ((5x + 2) cm + ( 2x +3)cm)
= 10x cm + 4 cm + 4x cm + 6 cm
= 14x cm + 10 cm
94 cm = 14x cm + 10 cm
94 - 10 cm = 14x cm
84 cm = 14 x cm
84 cm : 14 cm = x
6 = x
lebar = 2x cm + 3 cm = 12 cm + 3 cm = 15 cm
panjang = 5x cm + 2 cm = 30 cm + 2 cm = 32 cm