What quadrilaterals slopes of its opposite sides are equal and the slopes of its diagonals are opposite reciprocals.

Howdy;)

In a parallelogram, opposite sides are equal, opposite angles are equal and diagonals bisect each other. In a rhombus diagonals intersect at right angles. In a rectangle diagonals are equal. Five measurements can determine a quadrilateral uniquely.

8(-10x+3.5y-7)

8×-10x + 8×3.5y + 8×-7

-80x + 28y - 56

therefore

-80x+28y-56 is the correct answer