Calculate the atom economy for making hydrogen when zinc is reacted with HCL?

So, there are two parts to this question. 

Firstly, you need to decode the words in the question and transform this into an equation. 

From chemical knowledge, you know: acid + metal --> salt + hydrogen 

So now: HCL + Zn --> ZnCl2 + H2 .... then we balance this to give: 2HCL + Zn --> ZnCl2 + H2 

Secondly, we need to recall the atom economy equation (Mr of desired product / Mr sum of all products  x 100) i.e. what you need/everything produced  x 100  

Desired product Mr i.e. of H2 is: 1 x 2 = 2

All products Mr i.e. ZnCl2 + H2 is: 65 + (2 x 35.5) + (1 x 2) = 138 

2/138 x100 =1.45% :)