First of all, we put down 4:1 (the ratio of the length to width)
After, do 4+1
(Which equals 5)
And then do 45 divided by 5
(Equals 9)
Now, we have the width measurement, which is 9 inches
Since the length is 4 times the width, we put 9 x 4 to find the length
(Which equals 36)