Step-by-step explanation:
Steve correctly computed the change in x to be 2, and the change in y to be 6. However he put 2 in the slope formula for Δy (the change in y), and 6 for Δx. That is, Steve reversed the values of Δx and Δy.
The actual slope is ...
slope = Δy/Δx = 6/2 = 3