Write a function rule for the table. f(x) = x –1

f(x) = –1 – x

f(x) = x

f(x) = x + 1

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?