So,
Let "x" be the amount that we want to find.
We know that 15% of x equals 22.5. We could write this as the following equation:
![15\%(x)=22.5](https://img.qammunity.org/2023/formulas/mathematics/college/rwfty5q5ivgmukqgwayz3833w31tvxzs3z.png)
15% is the same to write 15/100. So,
![(15x)/(100)=22.5](https://img.qammunity.org/2023/formulas/mathematics/college/xumgeidqtkpbnwzb1byazcg30j9i2t9drq.png)
Now, let's solve this equation for x:
![\begin{gathered} 15x=22.5\cdot100 \\ 15x=2250 \\ x=(2250)/(15)=150 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/832qmo3uyco8rfrl3m4w86rsthdeogvr0o.png)
We can represent a percentage always dividing the number by 100:
For example,
![\begin{gathered} 50\%=(50)/(100) \\ \\ 45\%=(45)/(100) \\ \\ 20\%=(20)/(100) \\ \\ \text{and so on} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/292emwpkeawhd8i9f447yw9vt0v38314jv.png)
In this problem, we need to represent 15%, so that's 15/100. The only thing we did until then, was to rewrite the percentage. Then, just state the equation:
If 15% of x = 22.5, we should find x, so, we multiply by cross and obtain that x=150.