h=5; After plugging in the numbers, you end up with 45=9h. So we obviously need to solve this equation for h. Since 9 and h are being multiplied, we divide 9 to cancel 9 out and divided 9 on the other side as well (45/9=5). We are left with 5=h , therefore the solution is h=5.
We can check the answer by plugging in 5 for the base problem. 45=9(5). After multiplying 9 and 5 we end up with 45. 45=45 this is true therefore h=5 is a valid solution.