Plz explain. this to me will brainliest.

Which one ? is the answer and how to find this answer

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?

Multiplying fractions by whole number 5 x 1/3=?