Answer:
28:
y = -3/2x + 3
29:
y = x + 1
30:
y = 5/4x -2
Explanation:
Slope = Rise/Run
Just pick two points on the graph and count how much it goes up/down and left/right.
As for y-int, just see where the line touches the y axis.
Slope-intercept form:
y = mx + b
m is slope
b is the y-int