Answer
At $x_{1}, y_{1}$ is approximately 36.56 feet.
At $x_{2}, y_{2}$ is approximately 14.06 feet.
See graph:
Work Step by Step
$y=-\frac{3}{320}(x-80)^2+60$
$y_{1}=\frac{3}{320}(30-80)^2+60$
$y_{1}\approx 36.56 feet$
$y_{2}=\frac{3}{320}(150-80)^2+60$
$y_{2}\approx 14.06 feet$
