When solving an equation with two variables, replace the variables with the values given and then solve the now variable-free equation. (Remember order of operations, PEMDAS, Parentheses, Exponents, Multiplication/Division, Addition/Subtraction.)

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.

-5a - 1 = \( \frac{a}{1} \)
1 x (-5a - 1) = a
(1 x -5a) + (1 x -1) = a
-5a - 1 = a
-5a - 1 - a = 0
-5a - a = 1
-6a = 1
a = \( \frac{1}{-6} \)
a = -\(\frac{1}{6}\)

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.

4a - 3 < \( \frac{a}{-5} \)
-5 x (4a - 3) < a
(-5 x 4a) + (-5 x -3) < a
-20a + 15 < a
-20a + 15 - a < 0
-20a - a < -15
-21a < -15
a < \( \frac{-15}{-21} \)
a < \(\frac{5}{7}\)

You can only add or subtract monomials that have the same variable and the same exponent. For example, 2a + 4a = 6a and 4a² - a² = 3a² but 2a + 4b and 7a - 3b cannot be combined. However, you can multiply and divide monomials with unlike terms. For example, 2a x 6b = 12ab.

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).