Answer:
Step-by-step explanation:
In the equation y = mx + b, which is the form Ingrid's equation is in, the m stands for the rate of change. If the water level is decreasing, the rate at which it is decreasing is what goes in for m. The "b" of that equation indicates the starting height of the water, which is 170. The equation should be:
y = -4x + 170, negative because the water is decreasing.
