When your doing tax the tax is 9.25 you divide that by 100
the add that to your price then 12.5 divided by 100 and subtract that from what you ended up with so you should come out with a total of 4.22
Basically you just have to plug in g(x) wherever you see an x in the equation f(x) since x is f(x) you just substitute it . So f(g(x))=2x+3
You then just have to solve for 0
0=2x+3
Subtract 3 from both sides
-3=2x
Divide by 2
X=-3/2