Write the ratio in lowest terms:
7-1/2 inches to 3-1/3 inches

9:4

Step-by-step explanation:

I believe you meant:

   7 1/2 in

    3 1/3 in

Rewriting both mixed numbers as improper fractions, we get:

 15

   2

    10

      3

Remember:  to divide by a fraction (such as 10/3 here), invert the divisor fraction and multiply instead:

 15         3      (3)(3)

* = = 9/4 or 9:4  (this is a ratio expressed in lowest terms)

   2       10       (2)(2)