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.

2a⁹ - 6a⁹ = -4a⁹

A line on the coordinate grid can be defined by a slope-intercept equation: y = mx + b. For a given value of x, the value of y can be determined given the slope (m) and y-intercept (b) of the line. The slope of a line is change in y over change in x, \({\Delta y \over \Delta x}\), and the y-intercept is the y-coordinate where the line crosses the vertical y-axis.

The coordinate grid is composed of a horizontal x-axis and a vertical y-axis. The center of the grid, where the x-axis and y-axis meet, is called the origin.

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, isolate the variable for which you are solving (b) on one side of the equation and put everything else on the other side.

-9b + 7z = -5b + 3z - 1
-9b = -5b + 3z - 1 - 7z
-9b + 5b = 3z - 1 - 7z
-4b = -4z - 1
b = \( \frac{-4z - 1}{-4} \)
b = \( \frac{-4z}{-4} \) + \( \frac{-1}{-4} \)
b = z + \(\frac{1}{4}\)