Question 1021038
The probability of drawing a jack of spades is 1/52.
The probability of drawing a spade that is not a jack is 12/52, or 3/13.
The probability of drawing  jack that is not a spade is 3/52.
His expectation is thus

{{{0.50*(3/13) + 0.70*(3/52) + 0.85*(1/52) = 0.17}}}.

Therefore he should pay $0.17 for one draw.