Problem
Suppose a pharmaceutical company increases the price of insulin for a month's supply from $250 per month to $400 per month. At $250 per month, the equilibrium quantity is 100 per month. At $400 per month, the equilibrium quantity is 80. Calculate the price elasticity of demand and show the percentage change both Price and Quantity that you used to calculate elasticity (round to 1 decimal, e.g., 38.4% change in price).