Colin Buy gas for her car at $4 A gallon right and equation using two variables to show the relationship between the number of gallons of a gas g and the total amount she spends,s.

Let g represent the number of gallons of gas purchased and s represent the total amount spent. The equation can be written as:

s = 4g

This equation shows that the total amount spent (s) is equal to 4 times the number of gallons of gas purchased (g) at $4 per gallon.