To find the y-intercept, we need to re-arrange the equation given to y=mx+c, where c is the y-intercept
To do this to 5x + 4y = 12, we need to have only y on the left side, so subtract 5x from each side, to get
4y = 12 - 5x, or
4y = -5x + 12
Now we need to isolate y, so divide each side by 4
y = 5/4x + 3
So the y-intercept will be at +3, and the y intercept is always on x = 0, so the co-ordinate will be (0, 3), which is a.
