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.

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.

-4b - 4y = b + 5y + 2
-4b = b + 5y + 2 + 4y
-4b - b = 5y + 2 + 4y
-5b = 9y + 2
b = \( \frac{9y + 2}{-5} \)
b = \( \frac{9y}{-5} \) + \( \frac{2}{-5} \)
b = -1\(\frac{4}{5}\)y - \(\frac{2}{5}\)

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

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.

3a⁶ - 8a⁶ = -5a⁶

Parallel lines are lines that share the same slope (steepness) and therefore never intersect. A transversal occurs when a set of parallel lines are crossed by another line. All of the angles formed by a transversal are called interior angles and angles in the same position on different parallel lines equal each other (a° = w°, b° = x°, c° = z°, d° = y°) and are called corresponding angles. Alternate interior angles are equal (a° = z°, b° = y°, c° = w°, d° = x°) and all acute angles (a° = c° = w° = z°) and all obtuse angles (b° = d° = x° = y°) equal each other. Same-side interior angles are supplementary and add up to 180° (e.g. a° + d° = 180°, d° + c° = 180°).