Here are some questions that i just don't understand, please show working out. Thanks

Q1. ) A skateboard manufacturer finds that the cost $C of making X skateboards per day is given by C(x) = x^2-24x+244.
a)How many skateboards should be made per day to minimise the cost of production?

Q2) The driver of a car travelling downhill on a road applied the brakes. The speed (s) of the car in kmph, t seconds after the brakes were applied is given by s(t)= -4t^2 +12t+80.
a) How fast was the car travelling when the driver applied the brakes?
b) After how many seconds was the speed of the car 88 kmph? Can you explain your answer?
c) After how many seconds did the car reach its maximum speed?
d) What was the maximum speed reached?

Q3.) The hourly profit ($P) obtained from operating a fleet of n taxis is given by P(n) = 84n-45-2n^2.
a) What number of taxis gives the maximum hourly profit?
b) What is the maximum hourly profit/
c) HOw much money is lost per hour if no taxis are on the road?

Q4.) The temperature T Celsius in a greenhour t hours after susk (7.00 pm) is given by T(t)= 1/4 t^2-5t+30, (t<20)
a)what was the temperature in the greenhouse at dusk?
b) At what time was the temperature at a minimum?
c) What was the minimum temperature?




Thanks guys, i just really need ot know how to do it pronto.