IDENTIFYING PROPERTIES Identify the property being illustrated. 26. -3 + 3 = 0

27. (-6 + 1) + 7 = -6+ (1+7)

28. 9 + (-1) = -1 + 9

29. -8+0= -8

30. (x + 2) + 3 = X + (2+3)

31. y + (-4) = -4 + y

The weekly amount spent by a company for travel has an approximately normal distribution with mean = $550 and standard deviation = $40. a) what is the probability that the actual weekly expense will exceed $570 for more than 20 weeks during the next year? (note: one year = 52 weeks) b) what is the probability that actual weekly expenses exceed $580 for 10 or more, but 16 or fewer weeks during the next year?