Ax+z=aw-y solve for a. show work

So the question is asking to covert the said formula by making the a as the solution or the ask of the said equation, well in that matter, I would say, base on my own conversion and further computation about the said equation, the value of a is (y+z)/(x+w).  I hope this would help 

2,4,5,8,10 are divisible by 40

2015 they have a perecent