Answer:
Part 1) The slope is

Part 2) The slope is

Part 3) The slope is

Explanation:
Part 1) we know that
The equation of the line into slope intercept form is equal to

where
m is the slope
b is the y-coordinate of the y-intercept
In this problem we have

so
the slope is

Part 2) we know that
The equation of the line in standard form is equal to

where
the slope is equal to

in this problem we have

so

substitute


Part 3) we know that
The formula to calculate the slope between two points is equal to
we have
Substitute the values