CPM Homework Help : AC Problem 5-54

Joe drove $100$ miles from San Francisco to Gilroy and used $4$ gallons of gas. How much gas should he expect to use for a $3000$ -mile trip to New York City? Be sure to justify your reasoning.

Hint:

Set up a proportion with the information in the problem.

Step 1:

$\frac{\text{miles}}{\text{gallons}}=\frac{100}{4}=\frac{3000}{x}$

Step 2:

$\text{Solve for }x.$

$4\left(\frac{100}{4}\right)=\left(\frac{3000}{x}\right)4$

$x(100)=\left(\frac{12000}{x}\right)x$

$100x = 12000$

Answer:

$x=120$ gallons