Answer:
$3.50
Explanation:
Let x be the cost of per gallon gas.
We have been given that it costs Raquel 5$ in tolls to drive to work and back each day, plus she uses 3 gallons of gas. It costs her a total of 15.50$ to drive to work and back each day.
We can represent this information as:

Therefore, Raquel is paying $3.50 for per gallon gas.