Avehicular travels a distance of 5t^4-10t^2+6 miles in t+2 minutes

The complete question is
A vehicle travels a distance of 5t^4-10t^2+6 miles in t+2 minutes how fast is the vehicles speed

we know that
speed=distance/time
distance=5t^4-10t^2+6 miles
time=t+2 minutes
so 
You have to divide the distance by the time
speed=[5t^4-10t^2+6]/[t+2] miles/minute

the answer is
the speed is [5t^4-10t^2+6]/[t+2] miles/minute