Ashade of green paint is to be mixed with 3 parts blue and 2 parts yellow. ten gallons of green paint are to be mixed.

how many gallons of yellow paint must be used?

a.4.
b.2.
c.5.
d.6 2/3.

So here is the solution to the problem above.
Given that yellow is 2 parts and blue is 5 parts, that makes that a total of 5.
So yellow is 2/5 and blue is 3/5 of one gallon of green paint.
In order to know how many gallons needed for the yellow paint, we just simply multiply 2/5 by 10 and we get 20/5 or 4. Therefore, it needs 4 gallons of yellow paint, and the rest, 6 gallons is blue. Hope this answer helps.