Given the slope of the line segment and the end points, determine the value of the unknown.

Question

(15, 21), (12, y), slope = 6

Answer 1

Use the formula for slope. But this time the unknown will not be m, because you put 6 there.

The unknown will be y₂ (for which you substitute "y"). 

All of the other quantities x₁ y₁ and x₂ will also be known constants.

The job, then, is to solve for the unknown, "y".

Use your Algebra skills to ISOLATE y.

Answer 2

(y - 21)/(12 - 15) = 6

y - 21 = 6(12 - 15)

y - 21 = 6(-3)

y - 21 = -18

y = 3