Answer:
x=-9
Explanation:
B is unnecessary here, so we can ignore it. The first thing we do in this equation is simplify by adding like terms. 5a-10a=-5a. So, the equation is now -5a=45. To solve a, we need it by itself. To do that, we undo the multiplication by diving both sides of the equation by -5. 45 divided by -5 is -9, and then we have x=-9.