4.5w = 5.1w - 30 me with this question pls show the work

The depth of a lake at a certain point, wich is a function of the distance of that point from shore, is 30 feet.

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?

Find the solution of this system of equation -7x+y=-20 9x-3y=36