Step 1: See the relationship between the output, or y axis. In this example, the numbers go up by 3 each time.
Step 2: Take the number that they go up by (in this case it’s three), and incorporate it with the x axis, so it makes 3x. That’s the first part of the equation.
Step 3: Figure out the rest of the equation by replacing the x with the first number on the x axis. This might look like 3(1), which is three. To figure out the rest of the equation, figure out how the product can reach the number across from it on the y axis. In this example, it’s 6. So you would have to add three.
Step 4: To prove your point, try it with another example on the list.
3x + 3
3(3) + 3
= 9 + 3 = 12