To calculate the absolute price elasticity in this case, the expression is the quantity demanded change divided by the change in the price, both expressed as percentages. For the sandwiches, the demand dropped by (50/250), or 20% (0.20), while the price increased by (1.00/2.00), or 50% (0.50). The expression, then, would be (0.20/0.50), or a price elasticity of demand of 0.40.
