f(n) = f(n+1) +3
f(1) = f(2) +3
f(2) =f(3) +3
f(3) = f(4) +3
So f(1) = f(n) + 3* (n-1)
Put n=4 here so you found
f(1) = f(4) + 3* 3
= 22 +9
=31 ans
hope it helps
All it's asking is: How many cubic inches are there in 22 gallons ? And it already GAVE us the conversion factor !
The conversion factor is . . . . . 1 gallon = 231 cubic inches
Multiply each side by 22: 22 gallons = 22 x (231 cubic inches)
22 x 231 = 5,082
22 gallons = 5,082 cubic inches
If you empty a full 22-gallon tank out through that flow meter, the meter will register 5,082 cubic inches when the tank is empty.