To find the rate of change of the number of gallons in the wading pool, you can use the formula for the slope (rate of change) between two points \((x_1, y_1)\) and \((x_2, y_2)\):
\[ \text{slope} = \frac{y_2 - y_1}{x_2 - x_1} \]
Given the points \((1, 160)\) and \((3, 80)\), we can substitute these into the formula:
- \(x_1 = 1\), \(y_1 = 160\)
- \(x_2 = 3\), \(y_2 = 80\)
Substituting into the formula gives:
\[ \text{slope} = \frac{80 - 160}{3 - 1} = \frac{-80}{2} = -40 \]
Thus, the rate of change in the number of gallons in the pool after each hour has passed is \(-40\) gallons per hour.
The correct response is: −40 gal./hr.