Jenny has a stack of nickels and a stack of dimes. There are the same number of coins in each stack. Which expression represents the amount of money Jenny has, where n is the number of coins in each stack? Choose ALL that are correct.

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?