a video game costs $3.50 a month. You're total cost is $31.50
Let video games = x
You're equation is:
31.50 = 3.50x
Solve for x. Isolate the x. Note the equal sign. What you do to one side, you do to the other. Divide 3.50 from both sides
31.50/3.50 = 3.50x/3.50
x = 31.50/3.50
Divide
x = 9
9 is your answer
hope this helps