tolong lagi ya mohon dibantu

p = L+1 cm
L = L
kll = 30cm

kll persegi panjang = 2(p+L)
30 = 2(L+1+L)
30 = 2(2l + 1)
30 = 4l +2
30-2 = 4l
28 = 4l
L = 28/4
L = 7

panjang = L+1 = 7+1 = 8cm
lebar = l = 7cm

luas persegi panjang = p×l
8 × 7 = 56cm² ➡ D