Answer:
x=11
Explanation:
7x+13= 90 should be your equation.
when you solve you should have:
7x+13=90 but you want to start to solve so the first step would be to subract 13 from both sides because your adding 13 you wanna do the opposite of that and the opposite of addition is subtraction.
7x=77 now you wanna divide 7 from both sides
x=11