I don't understand your question completely, Leayah, but whenever you're given the slope of a line and it's y-intercept, you substitute those values into this equation:
y = mx + c
the value of the slope will be put in place of m, and c will be replaced with the value of the y-intercept.
For example, a line with crosses the y-axis at ( has a y-intercept of) -7 and has a slope of -2 will have the equation:
y = -2x - 7
