The initial value of an appliance is $700 and its value in the future is given by v(t)=100(2^(3-t)-1)

$\displaystyle v(t)=100(2^{3-t}-1)$ 0<=t<=3

where t is time in years. Thus after the first 3 years the appliance is worth nothing as far as the warranty is concerned. If it fails in the first 3 years, the warrantee pays v(t). Compute the expected value of the payment on the warranty if T has an exponential distribution with mean 5.

I have no clue where to start, help please