Train A and train b weigh a total of 343 tons. Train a is heavier than train b. The difference of their weights is 189 tons. What is the weight of each train

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?