What would the answer be to the question m - 7 < 6

Use set buikder notation to represent the following set: {, -2, -1, 0}

Icould really use some with this question.

Aparticular telephone number is used to receive both voice calls and fax messages. suppose that 25% of the incoming calls involve fax messages, and consider a sample of 25 incoming calls. (a) what is the expected number of calls among the 25 that involve a fax message?