Answer:
9
Step-by-step explanation:
Create a proportion
[tex]\frac{x}{12} = \frac{63}{84}[/tex]
84 divide by what gives you 12? 7
So divide 63 by 7, and you get 9.
This doesn't work with all of these problems so you can always cross multiply then divide.
12(63) = 756
84(x) = 84x
84x = 756
84x/84 = 756/84
x = 9
