Respuesta :

Solve as a proportion:

[tex] \frac{9}{12}= \frac{3}{x} [/tex]

x = ?

Cross multiply:-

3 × 12 = 36

Divide:-

36 ÷ 9 = x
36 ÷ 9 = 4
x = 4

9/12 = 3/4

The unknown denominator is 4. 
Do cross multiplication.

9              3
__   =        __
12            x

12×3=36. So now you found that out you will do a equation. Solve it.

9x=36
÷9   ÷9
________
x= 4

Now you got what the unknown denominator is. It's x=4. So 4.