First find the slope of the two points.
m = Δy / Δx
= (-3) - 3 / 6 - (-3)
= -6 / 9
= -0.67
Then assign one of the coordinates/ordered pairs as (x1,y1). Substitute the slope and the ordered pair and isolate y ( i used the first ordered pair).
y - y1 = m(x - x1)
y - 3 = -0.67(x + 3)
y - 3 = -0.67x - 2.01
y = -0.67x - 2.01 + 3
y = -0.67x + 0.99
Change the percent to a fraction, which is 70/100. Then multiply that fraction by 20.
(70*20)/100 = 1400/100
Move the decimal place over 2 spots to the left to get 14