Math
posted by Andrea on .
According to a rating agency, a car's MPG (miles per gallon) ratings are: 25 MPG for city and 30 MPG for highway driving. A driver spent $20.00 (the gasoline costs $1.25/gallon) on a combined city and highway trip of 450 miles. How many miles "C" in city and "H" on highway was the car driven ?
I need to put this into 2 equations. How does the $20.00 fit into the equation?

Change the 20 dollars to gallons.
Then,
gallons=citymiles/citympg + highwaymiles/Highwaympg