panjang dan lebar sebuah persegi panjang berturut turut (4x + 3)cm dan (5x - 5)cm. jika kelilingnya 50 cm, maka luasnya adlah?

K = 2(p + l)
50 = 2(4x + 3 + 5x - 5)
50 = 2(9x - 2)
50/2 = 9x - 2
25 = 9x - 2
25 + 2 = 9x
27 = 9x
x = 27/9 = 3

panjang = 4x + 3 = 4(3) + 3 = 12 + 3= 15 cm

Lebar = 5x - 5 = 5(3) - 5 = 15 - 5 = 10 cm

Luas = p x l
= 15 x 10
= 150 cm^2