Three of every seven sales transactions are dollar discount are on credit sales. what percent of the transaction are not credit sales?

Plz ( true - false) all triangles have interior angles whose measure sum to 90.

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?

Math i have no idea how to do a and b