Math Problem Statement

Write and solve the inequality

Car rental company A charges $45 a day to rent a certain car. Car rental B charges $30 a day plus $0.20 per mile to rent a similar car. For how many miles is the cost at car rental company B more than the cost at car rental company A for a one-day rental?

Solution

Let's analyze and break down the problem:

We have two car rental companies, A and B:

  • Company A charges $45 per day to rent a car.
  • Company B charges $30 per day plus $0.20 per mile driven.

The question asks: For how many miles driven is the cost at Company B more than the cost at Company A for a one-day rental?

Step 1: Set up the cost equations

Let xx be the number of miles driven.

  • Company A charges $45 for a day regardless of miles, so its total cost is: CA=45C_A = 45

  • Company B charges $30 per day plus $0.20 per mile, so its total cost is: CB=30+0.20xC_B = 30 + 0.20x

Step 2: Write the inequality

We want to find when the cost of Company B is greater than the cost of Company A, so we set up the inequality: 30+0.20x>4530 + 0.20x > 45

Step 3: Solve the inequality

Now, solve for xx:

  1. Subtract 30 from both sides: 0.20x>150.20x > 15

  2. Divide both sides by 0.20: x>150.20x > \frac{15}{0.20}

  3. Simplify: x>75x > 75

Conclusion

The cost at Company B will be greater than the cost at Company A when the number of miles driven exceeds 75 miles.


Would you like more details on how I solved this, or do you have any further questions?

Related Questions:

  1. How would the inequality change if Company A charged by the mile?
  2. What if Company B charged a higher per-mile rate, say $0.30 per mile?
  3. How would the solution change if Company A's daily rate increased?
  4. What if Company B had an additional flat fee?
  5. How can you represent this comparison graphically?

Tip: Always check the units and make sure they match when comparing costs!

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Math Problem Analysis

Mathematical Concepts

Inequality
Linear Equations

Formulas

Company A cost = 45
Company B cost = 30 + 0.20x

Theorems

Basic Inequality solving

Suitable Grade Level

Grades 7-9