5(x + 4) = 5x + 20 demonstrates what property?

One side of a rectangle is 7 feet shorter than seven times the other side. find the length of the shorter side if we also know that the perimeter of the rectangle is 306 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?

Cora bought a package of erasers. there are 4 pink erasers and 12 blue erasers. what is the ratio of pink erasers to blue erasers?