Question

# A family had dinner in a restaurant and paid 30 for the food. They also had to pay 9.5% sale tax and 10% for the tip. How much did they pay for the dinner?

Hint: Let us assume that we have to pay some x amount of money. Also, let us assume that we have to pay an extra y% money on the amount x. So, in total, we have to pay an amount of $x+\dfrac{xy}{100}$. Using this formula, this question can be solved.

In the chapter percentage, we have studied how to add a certain percentage to a number. For example, let us assume we have to pay some x amount of money. Also, we are required to pay an extra y% of the money x. So, the total money we have to pay will be equal to $x+\dfrac{xy}{100}.............\left( 1 \right)$.
In this question, it is given that the family had paid 30 for the food. It is given that they also had to pay 9.5% sale tax on this amount. So using formula $\left( 1 \right)$, we can say the total money they had to pay is equal to $30+\dfrac{9.5\times 30}{100}$.
Also, it is given that the family had to pay 10% tip on 30. So using formula $\left( 1 \right)$, the total money that they had to pay for the dinner is given by,
\begin{align} & 30+\dfrac{9.5\times 30}{100}+\dfrac{10\times 30}{100} \\ & \Rightarrow 30+2.85+3 \\ & \Rightarrow 35.85 \\ \end{align}