Hello all, we have this problem.

Suppose that the continuous random variable T has the Exponential distribution with expected value 4. Given that T = t, for any t > 0, the discrete random variable S has the Poisson distribution with expected value 3t.
Find:
a) E(S)
b) Var(S)

Can you help me out with this one? I struggle to find the answer, but i know its relatively easy .. Thank you.