Find y when x= 9, if y=-15 when x=27

Answer 1

From y = mx + b:

-15 = 27m + b

y = 9m + b

Then -15 − y = 18m or -y = m(18) + 15 or y = m(-18) − 15.

For (x,y) equal to (27,-15), y = m(-18) − 15 becomes -15 = m(27) − 15 which gives m = 0 and b = -15.

Then y = mx + b becomes y = (0)x + -15 or y = -15 and gives y equal to -15 when x = 9.