Given:
[tex]y=-\frac{1}{80}x^2+95[/tex]
Differentiate with respect to t
[tex]\frac{dy}{dt}=-\frac{1}{80}2x(\frac{dx}{dt})[/tex][tex]\frac{dy}{dt}=-\frac{1}{80}2(25)(8)[/tex][tex]\frac{dy}{dt}=-5[/tex]
The rate of change of elevation when x=25 is decreasing 5 feet/s .
