help me with this math

Question

What is the equation of the line that passes through the point (1,7) and has a slope of −1?

Answer 1

slope = -1

a line with slope -1 through the point (1,7)

slope also equals change in y coordinates divided by corresponding change in x coordinates

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

cross multiply

-x+1 = y-7

y= -x +1+7 = -x+8

y= -x + 8

or

x+y = 8 is the equation of the line with slope -1 through the point (1,7)