Question

What are the intercepts of the equation -3x + 4y = 12?

Answer 1

Find the x intercept by replacing y with 0
Find the y intercept by replacing x with 0

Answer 2

You've got that equation in so-called Standard form: Ax + By = C, neither A nor B = 0. As Mertsj said, you find the x-intercept by setting y = 0, and the y-intercept by setting x = 0, but once you understand that, you can take advantage of Standard form to know that the x-intercept is at (C/A, 0) and the y-intercept is at (0, C/B). It's a convenient form if you're going to graph the line, because you can read out the intercepts pretty much directly, plot the two points, and draw a straight line between them.