Question 55245
Let the months represent the x value and the ridership represent the y value.
January = x=1
February = x = 2
March = x = 3
April = 4, etc.
August = 8
.
So, the points are (1, 157) for January and (8, 543) for August.
Find the slope:
m = (543-157)/(8-1)=386/7 = 55.143
.
y=mx+b [Use the slope-intercept of a line]
157=(55.143)(1)+b [Plug-in the points and slope into the formula]
157=55.143+b [Solve for b]
101.86=b
.
y=mx+b [Plug-in the slope and y-intercept]
y=55.143x+101.86 
.
To find the ridership in April, let x=4; plug the values into the slope-intercept formula and solve for y.