Aprofessor must randomly select 4 students to participate in a mock debate. there are 20 students in his class. in how many different ways can these students be selected, if the order of selection does not matter?

Giuseppi's pizza had orders for $931.00 of pizzas. the prices were $21 for a large pizza, 514 for a medium pizza, and $7 for a small pizza. the number of large pizzas was two less than four times the number of medium pizzas. thenumber of small pizzas was three more than three times the number of medium pizzas. how many of each size of pizza were ordered?

What are the exclude value of mn+3m

Math it's appreciated. (picture provided)