Holt A2: p.28 #63

p.28 #63

A.  you are given two points...write the EQUATION.  (40,60) and (80,90)
m=(90-60)/(80-40)=30/40=3/4
y-60=(3/4)(x-40) OR y-90=(3/4)(x-80) OR y = (3/4)x + 30

B.  plug in x = 45...y =(3/4)(45) + 30 = 135/4 + 30 = 135/4 + 120/4 = 255/4 = 63.75

C.  plug in y = 84.  solve for x.  84 = (3/4)x + 30
54 = (3/4)x
72 = x