I don't understand this, may someone explain this too me thanks.

If i have 20$ and i gave 5$ away how much i got

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?

Which of the following circles have their centers in the third quadrant? check all that apply.