Final answer:
To make the same shade of green paint, the ratio of gallons of blue paint to gallons of yellow paint should be 5:9.
Step-by-step explanation:
To make the same shade of green paint, the ratio of gallons of blue paint to gallons of yellow paint should be the same as the ratio used by the house painter. In this case, the housepainter used a ratio of 5 gallons of blue paint to 9 gallons of yellow paint. So, the ratio should be 5:9.
For example, if you want to mix 10 gallons of green paint, you would need to use the same ratio. So, you would mix
10 * (5/9) = 5.55 gallons of blue paint and 10 * (9/9) = 10 gallons of yellow paint.