A taxi driver is going from LaGuardia Airport to Kennedy Airport at an average speed of v miles per hour. The distance is 30 miles and gas costs $1.33 per gallon. The taxi consumes gas at a rate of f(v)=2+(v^2)/(600) gallons per hour and v is between ten and 55. What average speed will minimize the total cost of fuel.

So far ive taken the derrivitave of f(v) to find the minimum but when you set that to 0 v=0 nad i need to find a value for v. Please help -->