Bonjour, URGENT ! NIVEAU 4eme merci

A 1ere face = x(x+5) = x²+5x
A 2eme face = (x+3)(x+5) = x²+5x+3x+15 = x²+8x+15
A 3eme face = x(x+3) = x²+3x

6 faces :
2(x²+5x) = 2x²+10x
2(x²+8x+15) = 2x²+16x+30
2(x²+3x) = 2x²+6x

Aire totale =
6x²+32x+30

x = 5
6(5)² +32x + 30 = 150+160+30 = 340