Find an equation of the line with the given slope and containing the given point. Write the equation in slope-intercept form.
13. Slope 3; (1, 2)
14. Slope 4; (5, 1)
15. Slope -2; (1, -3)
16. Slope -4; (2, -4)
17. Slope 1/2; (-6, 2)
18. Slope 2/3; (-9, 4)
19. Slope -9/10; through (-3, 0)
20. Slope -1/5; through (4, -6)