9- (-5)
Plz help me I don’t k is how to do this I got four but everything is telling me I’m wrong

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?

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25

What 8/12+8/11 in another way than and improper fraction