Answer: Subtracted 9.
Step-by-step explanation: To solve equations such as these, you always do the opposite than whatever the term is. For example, in your equation, "13" and "x" are MULTIPLIED together, which is why it's divided. The 9 is subtracted, which means it would need to be added to the other side.
Always remember that these equations are like scales- each side needs to be equal.
I hope this helps!
