At a tree farm, there are 9 rows of 36 spruce trees. in each row, 14 of the spruce trees are blue spruce. how many spruce trees are not blue spruce?

the answer to the question is a  

it has the same slope and the same y-intercept.

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: