15 × x² = 960
x² = 960 ÷ 15
x² = 64
x = √64
x = 8
length of the edge is 8 cm
2(8²) + 4(15 × 8) = 2(64) + 4(120)
= 128 + 480
= 608 cm²
total surface area is 608 cm²
now gimme brainliest
