Yg Nomer 17 caranya gimana?

L arsir = lt + pl
312 = 30x² + 48x²
312 = 78x²
4 = x²
2 = x

L = 2(pl +lt + pt)
= 2 (48x² + 30x² + 40x²)
L 2(118x²)
= 236x²
= 236(2²)
= 944