To solve this, you can use this helpful equation:
[tex]\frac{is}{of}[/tex] = [tex]\frac{percent}{100}[/tex]
Since you now have this equation, you can just plug in.
[tex]\frac{x}{15}[/tex] = [tex]\frac{20%}{100}[/tex]
To find x you would cross multiply, multiply the x with 100 and the 15 with the 20%.
100x = 300
Now to find x you would just divide both sides by 100.
x=3
