Keliling buku = 76 cmpanjang buku = 23 cmlebar buku = …….cm

Keliling persegi panjang= 2(p+l)
76= 2(23+l)
38= 23 + l
15 cm = l

Kll = 2 (p+l)
76 = 2 (23 + l )
76 / 2 = 23 + l
38 = 23 + l
l = 38 – 23
l = 15