The price of gasoline is $3.15 the price when Ryan's mother start drawing was 4/7 of the current price what was the price of the gasoline when Ryan's mother start driving

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?