I'm working on survey of calculus and I don't know what to do... If you could help one of these problems, that would be very helpful.

1)

A company knows that unit cost C and unit revenue R from the production and sale of x units are related by

by what??? Find the rate of change of revenue per unit when the cost per unit is changing by $8 and the revenue is $4000.

2)

The energy cost of a speed burst as a function of the body weight of a dolphin is given by

by what??? where w is the weight of the dolphin (in kg) and E is the energy expenditure (in kcal/kg/km). Suppose that the weight of a

dolphin is increasing at a rate of 5 kg/day. Find the rate at which the energy expenditure is changing with respect to time.

3)

Water is discharged from a pipeline at a velocity v given by v = 1226p(1/2)

(is the 1/2 an exponent? if so, use a caret (^) to indicate such), where p is the pressure (in psi). If the water pressure is changing at a rate of 337 psi/second, find the acceleration (dv/dt) of the water when

when???