(a): there is a 8/10 probability of pulling a 3 and a 2/10 probability of pulling a 5 so the expected value is \(\frac{8}{10}(3) + \frac{2}{10}(5)\) Expected value for drawing one slip of paper, this is equal to 3.4 or 34/10 or 17/5

(b): well, this would be the exact same idea except the probabilities are different, now the expected value is \(\frac{9}{11}(3) + \frac{2}{11}(5)\) which simplifies to 37/11

(c): Once again, same idea, the expected value would be \(\frac{10}{12}(3) + \frac{2}{12}(5)\) which simplifies to 10/3

If you have any questions, just ask :)