(8, 1) and (1, y); m = -1

Question

Find the value of y so that the line passing through the two points has a given slope.

Answer 1

Given points say (x1,y1) = (8,1)

(x2,y2) = (1,y)

given m = -1

Slope m =(y2-y1)/(x2-x1)

-1 = (y-1)/(1-8)

-1 = (y-1)/-7

Multiple to each side by negitive 7.

-1*-7 = -7(y-1)/-7

7 = y-1

Add 1 to each side.

7+1 = y-1+1

8 = y

y = 8