First, notice the the number of days goes up by 1 at a time. Each time the day goes up by 1, the cost goes up by 16. You can see that because 50 - 34 = 16; 66 50 = 16, etc. The rate of change is 16.
Now look at day 1 with cost 34. Since the rate of change per day is 16, if you subtract 1 day to find day 0, the cost for day 0 is 34 - 16 = 18. That shows that 18 is the fixed fee. The fixed fee is the y-intercept. The rate of change is the slope.
y = mx + b
The function is:
c = 16d + 18
Answer: c = 16d + 18
