Given: 5x-y=4. Create a couple of ordered pairs by choosing x and calculating y from this equation:
x=1 results in y=1. Thus, (1,1) is a solution.
x=-3 results in -15-y=4, or -y=19, or y=-19. Thus, (-3,-19) is a solution.
x=0 results in -y=4, so that y=-4. Thus, (0,-4) is a solution.