25a^3b^3-20a^5b^2+5a^3b^2 gives a new expression of the form U a^x b^y (Wa^2+Vb+Z) where U>0 . What's value of U ,V, x, W,Z, y

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?