An equation is two expressions separated by an equal sign. The key to solving equations is to repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

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 2 x 6) + (2 x 6 x 4) + (2 x 2 x 4)
sa = (24) + (48) + (16)
sa = 88

To solve this equation, repeatedly do the same thing to both sides of the equation until the variable is isolated on one side of the equal sign and the answer on the other.

-4c + 2 = \( \frac{c}{3} \)
3 x (-4c + 2) = c
(3 x -4c) + (3 x 2) = c
-12c + 6 = c
-12c + 6 - c = 0
-12c - c = -6
-13c = -6
c = \( \frac{-6}{-13} \)
c = \(\frac{6}{13}\)

An isosceles triangle has two sides of equal length. An equilateral triangle has three sides of equal length. In a right triangle, two sides meet at a right angle.

A rhombus is a parallelogram with four equal-length sides. A square is a rectangle with four equal-length sides.