Nomor 15 yg tadi salah

panjang = 5x
lebar = 3x
tinggi = 2x
5x × 3x × 2x = 810
30x³ = 810
x³ = 27
x = 3 cm
panjang = 5x = 15 cm
lebar = 3x = 9 cm
tinggi = 2x = 6 cm
Lp = 2×p×l + 2×p×t + 2×l×t
= 2×15×9 + 2×15×6 + 2×9×6
= 270 + 180 + 108
= 558 cm²