Please help with this one!

Name the most appropriate metric unit for each measurement

Mrs. morton has a special reward system for her class. when all her students behave well, she rewards them by putting 3 marbles into a marble jar. when the jar has 100 or more marbles, the students have a party. right now, the the jar has 24 marbles. how could mrs. morton reward the class in order for the students to have a party?

What value of x is in the solution set of 4x – 12 s 16 + 8x?