Question

A barrel contains 109 gallons of water and is being drained at a constant rate of 7 gallons per hour. Write the equation that modles the number of gallons,g, after t hours.

Answer 1

After t hour, gallons in the barrel =
109 - (t *7)
After 1 hour, gallons in the barrel =
109 - (1 *7)
= 102 gallons

Answer 2

Or to make it just like the question:
g = 109 - (t *7)