what is meant by slope of budget line and it's derivation plssss explane me with n example??????????

The slope of the budget line measures the amount of good 1 that must be foregone (sacrificed) in order to obtain an additional unit of good 2. It is represented as,

The following is the mathematical derivation of the slope of budget line.

In the above diagram, point B represents the initial consumption bundle where 4 units of good 1 and 2 units of good 2 are demanded. On the other hand, Point A represents the final consumption bundle where 3 units of good x and 4 units of good y are consumed. With a movement from point B to point A, the quantity of good x falls to 3 units, i.e. Δx = (4 - 3) = 1 unit. On the other hand, the quantity of good y rises to 4 units i.e. Δy = (4 - 2) = 2 unit. 

Hence, Slope =