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Example 9.58 from Prealgebra, 9.7 Solve a Formula for a Specific Variable
Rey is planning to drive from his house in San Diego to visit his grandmother in Sacramento, a distance of miles. If he can drive at a steady rate of miles per hour, how many hours will the trip take?
Work it out on paper first. Then open the solution one step at a time, and stop as soon as you can finish on your own.
| Step 1. Read the problem. Summarize the information in the problem. |
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| Step 2. Identify what you are looking for. | how many hours (time) |
| Step 3. Name: Choose a variable to represent it. |
let t = time |
| Step 4. Translate. Write the appropriate formula. Substitute in the given information. |
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| Step 5. Solve the equation. | |
| Step 6. Check: Substitute the numbers into the formula and make sure the result is a true statement. |
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| Step 7. Answer the question with a complete sentence. We know the units of time will be hours because we divided miles by miles per hour. |
Rey's trip will take 8 hours. |
The book's Try It right after this example: same idea, new numbers. Only the answer is given.
Lee wants to drive from Phoenix to his brother’s apartment in San Francisco, a distance of miles. If he drives at a steady rate of miles per hour, how many hours will the trip take?
How did it go?