The radius of a circle is 21 cm, what is the area?​

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 nonpermissible replacement for binthis expression.b2/5b +5

What is the solution to this system of equations? y= 2x - 3.5 x - 2y = -14