Question

Alex rents a car for one day. The charge is $\$18$ plus $\$0.12\mathrm{per}\mathrm{mile}$. Alex wants to spend exactly $\$30$. How many miles can he drive?

Answer 1

Compute the miles Alex can drive:

Let $x$ be the mile, he drive the car

According to question

$18+0.12x=30$

$$\begin{gathered} \Rightarrow 18-30=-0.12x\left[\mathrm{Grouping}\mathrm{the}\mathrm{like}\mathrm{terms}\right] \\ \Rightarrow -12=-0.12x\left[\mathrm{Divide}\mathrm{both}\mathrm{sides}\mathrm{by}-0.12\right] \\ \Rightarrow x=\frac{12}{0.12} \\ \therefore x=100\mathrm{miles} \end{gathered}$$

Hence, Alex can drive $100\mathrm{miles}$.