How do you solve question 1

For each proportion find the unknown number x 1/5/8=×/15

Simplify. (-2)^-3 a. -8 b. -1/8 c. 1/8 d. 8

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?