Find the slope of a straight line from two points on it

Follow this one with me, a step at a time. Try to guess each step first.

Worked example 1

Find the slope of the straight line passing through A(2, 3) and B(−3, −4).

Remember: Slope is the vertical change divided by the horizontal change. Subtract in the same order on the top and on the bottom.

Slope = (y₂ − y₁) ÷ (x₂ − x₁), taking B as the second point.
The vertical change is (−4) − 3 = −7 and the horizontal change is (−3) − 2 = −5.
The slope is −7 ÷ (−5), which is 7/5.

Common mistakes

Put the horizontal change over the vertical change. Slope is the vertical change divided by the horizontal change.
Subtracted the coordinates in different orders, so the sign is wrong. Use the same point first in both.
Used one point only, as if the line passed through the origin.