Question

If 10.5 gm of an alloy of copper and zinc contains 2.1 gm of zinc , find the weight of the copper in 42 gm of the alloy.
The answer is given - 33.6 gm.
please give step by step explanation because i need to write in school copy. Please help if you know this is Unitary Method chapter.​

Answer 1

alloy 10.5

zinc 2.1

copper = 8.4 gm.

if 10.5 gm alloy then copper is 8.4 gm

if 1 gm alloy then copper is 8.4/10.5

if 42 gm alloy then copper is 33.6gm.