Answer: it contains 200 grams of zinc.
Explanation:
Ratio of zinc to copper is 4 to 15 = 4;15
Total ratio = 4+15= 19
We first find amount of both zinc and copper( the whole chemical) which is equal to
ratio of copper / total ratio x (the entire chemical--total grams of zinc and copper) =amount of copper
15/19 x X = 750
X= 750 X 19 / 15= 950 grams
To find amount of zinc in the chemical = ratio of zinc / total ratio x total amount of chemical
=4/19 x 950
=200 grams