Answer:
y = -0.2x + 8
Step-by-step explanation:
To write a linear function, calculate the rate of change of the gallon of water leaving the tank and the starting level.
The function will describe the number of gallons over time or (time, gallons).
This means the function has data points (1, 7.8) and (9, 6.2).
Use the rate of change or slope formula to calculate it.
This means that for the formula y = mx+b then m = -0.2.
This also means that after losing 0.2 gallons the first hour it was at 7.8. So the starting value is 8 gallons.
The equation is y = -0.2 x + 8.