Respuesta :

9 will be your answer

5 x 3 = 15, therefore, 3 x 3 = 9

because you multiplied 3 for 5, you will be doing the same for 3, which means 3 x 3

hope this helps
ratios are nothing but equivalent fractions

3/5 = 9/15 = 12/20...so ur missing number is 9