To combine like terms, add or subtract the coefficients (the numbers that come before the variables) of terms that have the same variable raised to the same exponent.

9a - 3a = 6a

A right angle measures 90 degrees and is the intersection of two perpendicular lines. In diagrams, a right angle is indicated by a small box completing a square with the perpendicular lines.

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 < sign and the answer on the other.

-8a + 6 < \( \frac{a}{-6} \)
-6 x (-8a + 6) < a
(-6 x -8a) + (-6 x 6) < a
48a - 36 < a
48a - 36 - a < 0
48a - a < 36
47a < 36
a < \( \frac{36}{47} \)
a < \(\frac{36}{47}\)

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

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).