College calculus: i've having a lot of trouble with these an explanation would be great !

Leslie started last week with $1200 in her checking account. during the week, she wrote the checks below.

How many verticies does a triangular prims have

The area (a) of a circle with a radius of r is given by the formula and its diameter (d) is given by d=2r. arrange the equations in the correct sequence to rewrite the formula for diameter in terms of the area of the circle.