Calculate the difference between the x-coordinates of the points by subtracting the first x-coordinate from the second x-coordinate. For example, if your points are (-3,-5) and (0, 4), subtract -3 from 0 to get 3.
Calculate the difference between the y-coordinates of the points by subtracting the first y-coordinate from the second y-coordinate. For example, if your points are (-3,-5) and (0, 4), subtract -5 from 4 to get 9.
Divide the x-coordinate difference by the y-coordinate difference to find the slope. In this example, divide 3 by 9 to get 1/3.
Calculate the product of the slope and the first x-coordinate. In this example, multiply 1/3 by -3 to get -1.
Subtract the product of the slope and the first x-coordinate from the first y-coordinate from the first y-coordinate to find the y-intercept. In this example, subtract -1 from -5 to get a y-intercept of -4.