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
Area of the square bottom = L x W = 5 x 5 = 25 square cm
Area of triangle = 1/2 x base x height = 1/2 x 5 x 6 = 15 square cm
Total area = 25 + 15 = 40 square cm.