The rate at which a sewing machine operator's efficiency E (expressed as a percentage) changes with respect to time is given by dE/dt = 40 - 10t, where t is the number of hours the operator has been at work

a) Find E(t), given that E(2) = 72, (i.e. the operator's efficiency after working 2 hours is 72%.

b) What is the maximum and minimum efficiency of the machine during the first 8 hours?

c) Find the area between the graphs of y = e ^x and y = x, for values of x between x = 2 and y-axis.