What's the answer to 9-2x=35 using distributive property pl HELP

I'm so close to finishing all these.

Find the value of the cosine for angle a

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?