Total cost
The cost of a manicure is $25.
We want to find the 20% of $25. We have the following equivalence
20% → ?
100% → $25
If we divide each side of the equivalence we will have the same answer
![\begin{gathered} (20)/(100)=(?)/(25) \\ (1)/(5)=(?)/(25) \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/8ax0skqq9kcew1xlyyvfjg6svxbwzkwenr.png)
Multiplying both sides by 25 we have:
![\begin{gathered} 25\cdot(1)/(5)=\text{?} \\ 5=\text{?} \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/vhqy8wgqnuzculzuv5vvpidatzfge422x6.png)
Then the person decides to leave $5 (that is the 20% of $25)
Then, the total cost including the tip is $25 + $5 = $30
Answer: $30