Be quick! i need this as soon as possible!

What number should be added to both sides of the equation to complete this square? x^2-10x=7

A, b, c, and d have the coordinates (-8, 1), (-2, 4), (-3, -1), and (-6, 5), respectively. which sentence about the points is true? a. a, b, c, and d lie on the same line. b. and are perpendicular lines. c. and are parallel lines. d. and are intersecting lines but are not perpendicular. e. and are parallel lines.

3x + 4y = 5 x- 3y = -7 solve by substitution