Answer:
f(3)=275, f(5)=325
Explanation:
We just plug in 3 and 5 into the equation:
We get f(x) = 25x + 200
f(3) = 25*3 + 200
=75+200
=275
Interpretation: if there are three cell phones on the plan, then the total monthly cost is 275.
for f(5):
f(5) = 25*5 + 200
=125+200
=325
Interpretation: if there are five cell phones on the plan, then the total monthly cost is 325.