Answer:
a) 
b) 
c) term number 17 is the one that gives a value of 40
Step-by-step explanation:
a)
The sequence seems to be arithmetic, and with common difference d = 3.
Notice that when you add 3 units to the first term (-80, you get :
-8 + 3 = -5
and then -5 + 3 = -2 which is the third term.
Then, we can use the general form for the nth term of an arithmetic sequence to find its simplified form:

That in our case would give:

b)
Therefore, the term number 20 can be calculated from it:

c) in order to find which term renders 20, we use the general form we found in step a):

so term number 17 is the one that renders a value of 40
Answer:
a) -3 gallons per hour
b) y = -3x +14
Step-by-step explanation:
Rate of change is computed by dividing the amount of change by the interval over which it occurred.
<h3>a)</h3>
Here the amount of gas decreased from 14 to 2 gallons, so a decrease of 14-2 = 12 gallons. That occurred over a 4-hour period, so the rate of change is (-12 gallons)/(4 hours) = -3 gallons/hour.
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<h3>b)</h3>
The initial amount was 14 gallons, so the equation for the line describing remaining gas will be ...
y = -3x +14 . . . . gas in the tank after x hours