Solve the Problem $v$ (In $\mathrm{mph}$ ) When the Brakes Are Applied, the Distance

Solve the problem.
-For a motorcycle traveling at speed $v$ (in $\mathrm{mph}$ ) when the brakes are applied, the distance $\mathrm{d}$ (in feet) required to stop the motorcycle may be approximated by the formula $\mathrm{d}=0.05 \mathrm{v}^{2}+\mathrm{v}$ . Find the instantaneous rate of change of distance with respect to velocity when the speed is $49 \mathrm{mph}$ .

A) $11.8 \mathrm{mph}$
B) $4.9 \mathrm{mph}$
C) $5.9 \mathrm{mph}$
D) $50 \mathrm{mph}$