So this is what I came up with, please tell me if I'm wrong...
The daily sale of lunch is a random variable. Let us call it X. X ~ N (70,9). What is the probability that in a given day the restaurant sells more than 75 lunches?
Is this telling me that the population average is 70 lunches with variance of 9?
5/3 = 1.67 (correct to two decimal places) not 1.68.
Also, I don't see the point in rounding z to two decimal places and then giving a probability to four decimal places.
Either use a more accurate value of z or round the probability to less than four decimal places. (Personally I'd do the former).