If the charge is a linear function, we need to find the slope
of the line. In this problem, money charged is a function
of hours parked... f(h) = $
Your points then are (hours, dollars)
We have two points... (4, 5.5), (7, 7.75)
The slope is the rise over the run...
m = (7.75 - 5.5)/(7-4) = 2.25/3 = .75
If the hours decrease by 1, the charge will decrease by $.75.
At 4 hours we charge, $5.50
For 3 hours we charge $5.50 - $.75 = $4.75
