NOMOR 12 DONG. PLEASE :) tq.

Jawaban ada di lampiran.

K = 2 (p + l)
42 = 2 {(3x – 2) + (x + 3)}
42 = 2 { 3x + x – 2 + 3 }
42 = 2 { 4x + 1 }
42 = 8x + 2
42 – 2 = 8x
40 = 8x
x = 40 / 8
x = 5
p = (3x – 2) = 3 (5) – 2 = 15 – 2 = 13
l = (x + 3) = 5 + 3 = 8
Luas = p × l = 13 × 8 = 104