Question

A family of four had dinner together at a restaurant. Write two expressions for calculating their total bill if they leave a 15% tip. Let c represent the cost of their meal before tipping.

Answer 1

Expression of total bill is t = 1.15c where t represents total bill and c represents cost of the meal before tipping.

Solution:

Given that family of four had dinner together at restaurant.

Percentage of tip left by family = 15%

Cost of the meal before tipping is represented by variable c.

Need to determine expression for total bill paid.

Let’s assume total bill be represented by variable t.

total bill = cost of the meal before tipping + 15% of tip

15% of tip means 15% of cost of meal before tipping.

=> Total bill = cost of the meal before tipping + 15% of cost of meal before tipping.

 On substituting given variable c and assumed variable t in above expression, we get

t = c + 15% of c

$\begin{array}{l}{\Rightarrow t=c+\frac{15}{100} c} \\\\ {\Rightarrow t=\frac{100 c+15 c}{100}=\frac{115 c}{100}} \\\\ {\Rightarrow t=1.15 \mathrm{c}}\end{array}$

Hence required expression of total bill is t = 1.15c where t represents total bill and c represents cost of the meal before tipping.