What is the answer 2/4

Determine whether the set of whole numbers is closed under addition. explain why the set is or is not closed. give an example.

The number of chocolate chips in an 18-ounce bag of chocolate chip cookies is approximately normally distributed with a mean of 1252 chips and standard deviation 129 chips. (a) what is the probability that a randomly selected bag contains between 1100 and 1500 chocolate chips, inclusive? (b) what is the probability that a randomly selected bag contains fewer than 1125 chocolate chips? (c) what proportion of bags contains more than 1225 chocolate chips? (d) what is the percentile rank of a bag that contains 1425 chocolate chips?

Does anyone know how to solve and graph this: 4 + | a + 2 | < 7the only part i don't get is the "4 +"