Hi
Using the standard slope-intercept form for an equation of a line y = mx + b
where m is the slope and b the y-intercept.
1. slope is -5; y-intercept 1/2
y = -5x + 1/2
2. slope -3, through (0,-5)
y = -3x + b |using ordered pair Pt(0,-5) to solve for b
-5 = -3*0 + b
-5 = b
y = -3x - 5