I'm assuming the box is a rectangular prism:
They're asking for the surface area so the answer should be 48*2 + 192*2 + 36*2 since it has 6 faces so S.A. = 552 square in.
The answer would be, y - 32 + 4y
Zinc = 7/18
Divide 4.9 by 7 = 0.7
Multiply by 18 = 12.6
The answer is 12.6 lbs of alloy. Sorry if I'm wrong