(0,50),(1,75)
slope = (75 - 50) / (1 - 0) = 25/1 = 25
y = mx + b
slope(m) = 25
y int (b)....this is when x = 0...u have (0,50)...meaning ur y int is 50
now just sub
y = 25x + 50 <== ur equation
the y int is 50 or (0,50).....this represents the one time registration fee.