There is only two multiples of three on a six-sided die, the 3 side, and the 6 side.
3 x 20 = 60
6 x 20 = 120
120 + 60 = 180
$180.00 is your possible winnings total, but the question asks for your expected value on EACH roll, so you divide 180 by 6(sides on a die) to get your final answer
180/6 = 30
ANSWER: D. $30.00