To make orange paint, Pedro mixes red paint and yellow paint in the ratio 3:2. If he uses 8.5 gallons of yellow paint, how many gallons of red paint does he use?
You can set up the equation 3y=2r, with r standing for the amount of red paint in gallons, the same going for y. If you substitute in 8.5 for y, you get that 2r=25.5. Divie each side by 2, and r=12.75. So, Pedro uses 12.75 (or 12 and three-fourths) gallons of red paint.
