Solve for the missing elements. Show your work. Use 3.14 for pie 28 diameter​

Atriangle has an area of 72 square inches. if the base of the triangle has a length of 18 inches, what is the height of the triangle? use the formula for the area of a triangle: area = (base)(height) type a numerical answer in the space provided. do not include the units or spaces in your answer.

Christina can paint 420 square feet in 105 minutes. which unit rate describes the scenario?

Which equation results from adding the equations in this system? x+6y=9 and -x+2y=-15