How do i solve this equation!

Factor the expression using the gcf. the expression 21m−49n factored using the gcf

Plz hurry evaluate the expression a+b where a=8 and b=19

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?