This problem forces us to assume that Pedro has just entered the toll road. He has gone no miles on the toll road yet.
x, miles traveled on the toll road
y, the toll to be paid for x miles
According to his plan, (5, 1.75), an (x,y) point.
According to what happened, (9, 2.75), another point.
Slope m:
%282.75-1.75%29%2F4
m=1%2F4
Picking the "plan" point and found slope
and putting into point-slope equation form:
y-1%263%2F4=%281%2F4%29%28x-5%29
Simplify and put into slope-intercept form:
highlight%28y=x%2F4%2B1%2F2%29
highlight%28y=x%2F4%2Bhighlight_green%281%2F2%29%29
The y-intercept is 1%2F2.
