You are solving for n. First you want to get n by itself on one side of the equal sign. To do this you need to get rid of the -5, so you add it to both sides.
So you need to solve for x. To do so you need to isolate the variable first. This is what you do.
13 = x - 5 You add 5 to both sides to get x by itself. 18 = x So now lets check our work by plugging in the variable! :) 13 = 18 - 5 13 = 13 It is a solution so 18 is your answer. I hope this helps love! :)