The normal xy graph consists of a horizontal line that represents the x axis and a perpendicular line that runs through the middle of the x axis which represents the y axis. Where the two intersect is given a designation of 0,0. One of the most important relationships of the xy graph is the line called the "slope" or angle of the line from the center point. Finding the y value is easy if you know the slope of the line and the x coordinate.

Review the equation for the slope of a line. The equation for finding the slope is: m = [y1 - y2] / [x1 - x2]. If you know x, you can solve for y to find the y value for the slope of the line.

Define your variables. Graph a line with the following equation: y = -(2/3)x + 3.

## Sciencing Video Vault

Choose any variable for x along the line. Say you choose 3. If x = 3, then y = -2 (( 2/3 )(3) – 4 = 2 – 4).