Answer:
12
Step-by-step explanation:
Using proportionalities....
[tex]\frac{15}{5} =\frac{9}{3} =\frac{x}{4}[/tex]
( use one proportionality to solve for x )
[tex]\frac{15}{5} =\frac{x}{4}[/tex]
* simplify expression *
15 / 5 = 3
[tex]3=\frac{x}{4}[/tex]
* multiply each side by 4 *
[tex]3 * 4 = 12\\\frac{x}{4} *4=x[/tex]
we're left with x = 12
