Answer:
-3x + 40
Step-by-step explanation:
The constant given is 40 gallons and the rate at which the water in the bathtub decreases is 3 gallons per minute.
To write this as an equation we model 40 as the starting constant that is positive and, because the water is decreasing, we use a negative slope.
-3x represents the decrease in water over x intervals (Which in this case is minutes) and 40 gallons represent the initial value (water in the bathtub).
Therefore the water in the bathtub can be modeled with the equation
-3x + 40
