A rectangle is a parallelogram containing four right angles. Opposite sides (a = c, b = d) are equal and the perimeter is the sum of the lengths of all sides (a + b + c + d) or, comonly, 2 x length x width. The area of a rectangle is length x width. A square is a rectangle with four equal length sides. The perimeter of a square is 4 x length of one side (4s) and the area is the length of one side squared (s²).

Perimeter is equal to the sum of the four sides:

p = a + b + c + d
p = 8 + 6 + 2 + 6
p = 22

Angles around a line add up to 180°. Angles around a point add up to 360°. When two lines intersect, adjacent angles are supplementary (they add up to 180°) and angles across from either other are vertical (they're equal).

The surface area of a cube is (2 x length x width) + (2 x width x height) + (2 x length x height):

sa = 2lw + 2wh + 2lh
sa = (2 x 3 x 7) + (2 x 7 x 4) + (2 x 3 x 4)
sa = (42) + (56) + (24)
sa = 122

The first step to solve a quadratic equation that's set to zero is to factor the quadratic equation:

c² + 6c + 8 = 0
(c + 2)(c + 4) = 0

For this expression to be true, the left side of the expression must equal zero. Therefore, either (c + 2) or (c + 4) must equal zero:

If (c + 2) = 0, c must equal -2
If (c + 4) = 0, c must equal -4

So the solution is that c = -2 or -4