Please help with this

x = 5

Step-by-step explanation:

The sides are in proportion.

The proportion is 20/36

The other sides must be in the same proportion: 5x / 45

5x/45 = 20/36        You can reduce the left side by dividing top and bottom by 5

1x / 9 = 20/36          You can reduce the right side by dividing by 4

x / 9 = 5/9                at this point you should be able to see that x = 5, because the denominators are the same.

That is the answer.

However you can extend this by cross multiplying

9x = 45                      Divide by 9

x = 45/9

x = 5