How do I solve 3x+7+x?

What is the difference between regular convex and concave polygons

Aquadrilateral has exactly one pair of parallel sides. which name best describes the figure?

Someone answer this asap for the length, in feet, of a rectangular rug is represented by the expression 5x² + 2x. the width, in feet, is represented by the expression 3x². which expression represents the perimeter, in feet, of the rug? a. 8x² + 2x b. 8x² + 4x c. 16x² + 2x d. 16x² + 4x