How do you the expectation

Question 1 (1 point) Solve the problem. Bob and Fred play the following game. Bob rolls a single die. If an even number results, Bob must pay Fred the number of dollars indicated by the number rolled. Or the other hand, if an odd number is rolled, Fred must pay Bob the number of dollars indicated by the number rolled. Find Bob's expectation. a) $0.40 b) $0.00 c -50.25 d) - 50.50