Chapter 8, Problem 60CR

To determine

How many cars must he detail weekly to earn at least $350 a week

Answer to Problem 60CR

He detail weekly to earn at least $350 is $15$

Explanation of Solution

Given:

At the car wash. Xander receives $200 a week plus $10 for every car he details

Concept Used:

• If there is the strict inequality symbol $<\text{ or}>$ , then use a parenthesis $\left(\right)$ on the interval
• If there is the inequality symbol $\le \text{ or}\ge$ , then use a bracket $\left[\right]$ on the interval

Calculation:

In order to find the enquality. Let x be the number of cars he details. Xander receives $200 a week plus $10 for every car as below:

  $\begin{array}{c}350\le 200+10x\\ 350-200\le 200+10x-200\\ 150\le 10x\\ \frac{150}{10}\le \frac{10x}{10}\\ 15\le x\end{array}$

Thus, he detail weekly to earn at least $350 is $15$