Compute a slope of linear supply function

Hi Krishna. Good question. Here is my solution.

When price increases, quantity supply increases.
When price decreases, quantity supply decreases.

Slope of linear supply function = $\frac{\Delta Q^s}{\Delta P}$ = $\frac{\text{Change in quantity supply}}{\text{Change in price}}$ = $\frac{Q_2^s \, - \, Q_1^s}{P_2 \, - \, P_1}$