a certain color paint should have a mix of blue and green and a ratio of 5:2 if a house painter needs to use 8 gallons of green paint how many gallons of blue paint should he mix with it in order to obtain the right color

He needs 20 gallons of blue paint in order to obtain the right color.

Step-by-step explanation:

A certain color paint should have a mix of blue and green and a ratio of 5:2

i. e. he needs to mix 5x quantity of blue paint and 2x quantity of green paint

A house painter needs to use 8 gallons of green paint.

⇒ 2x=8 gallons

⇒ x=4 gallons

So, He needs 5*4 gallons of blue paint

i. e. He needs 20 gallons of blue paint in order to obtain the right color.

20 Gallons

Step-by-step explanation:

blue:green

5:2

Green paint is 8 gallons

Plug 8 gallons into the ratio and get ...

20:8

There are 20 gallons of blue paint