Please help me and explain with a good answer

Prove that quadrilateral is a rhombus.

Complete the solution of the equation. find the value of y when x equals to 6 4x+y=20

Adecorative window is made up of a rectangle with semicircles at either end. the ratio of ad to ab is 3: 2 and ab is 30 inches. what is the ratio of the area of the rectangle to the combined area of the semicircles? possible answers: a. 2: 3 b. 3: 2 c. 6: π d. 9: π e. 30: π