The area of the base (six triangles with a base 15m and a height 7.5√3m):

The area of side walls (six triangles with a base 15m and a height 12m)

The surface area:
Answer:
x²y²+xy²+3+xy+2y²
Step-by-step explanation:
(2x²y²+x²y+xy²+3)-(x²y²+x²y²+x²y-xy-2y²)
1. remove the parentheses (when there’s - in front of an expression in parentheses change the sign of each term of the expression)
2x²y² + x²y + xy² + 3-x²y² - x²y² - x²y + xy - 2y²
2. eliminate the opposites
2x²y² + xy² + 3 -x²y² + xy +2y²
3. collect like terms
x²y² + xy² + 3 + xy + 2y²
Just add 5 on both sides:
x-5>10
x>15