Nikki mixes yellow and blue paint in a ratio of 2:5 to make green paint. How many gallons of blue paint will Nikki needs to make a total of 35 gallons of green paint?

Answer 1

Gallons of Blue Paint + Gallons of Yellow Paint = 98 Gallons Paint
can be written as B + Y = 98

Ratio of Blue Paint to Yellow Paint = 3:4
can be written as B/Y = 3/4

equation 1: B + Y = 98
equation 2: B/Y = 3/4

next step, get B by itself by multiplying both sides of equation 2 by Y
This will give you B = 3/4Y or converting fraction to decimal, B = .75Y

Substitute this value of B into equation 1 to get .75Y + Y =98

leading to 1.75Y = 98
solving for Y = 56
B + Y = 98 , solving for B = 42
42 gallons blue paint
56 gallons yellow paint

Answer 2

Phew, that solution is complicated, and the answer doesn't even make sense, and doesn't even match the question.

let the number of gallons of yellow paint be 2x
let the numbe of gallons of blue paint be 5x, (note 2x : 5x = 2:5)
2x + 5x = 35
7x = 35
x = 5

needed: 10 gallons of yellow and 25 gallons of blue

check: 10+25 = 35, check!
ratio of 10:25 = 2:5, check!