PLS HELP ME ITS MULTIPLE CHOICE

There are 15 plates and each plate is either 7 or 12 inches diameter. which systems of equations do you use to find the number of 7 inch plates, x and 12 inch plates, y

Manny bought 12 pounds of vegetables at the supermarket. 75% of the vegetables were on sale. how many pounds of vegetables were not on sale? 98 points : )

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?