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.