When the price of bubble gum is $0.50, the quantity demanded is 400 packs per day. When the price falls to $0.40, the quantity demanded increases to 600. Given this information and using the midpoint method, you know that the demand for bubble gum is

elastic

could someone go over the math part so I can understand why it is elastic

The following are line items from the horizontal analysis of an income statement:increase/ (decrease) increase/ (decrease) 2017 2016 amount percent fees earned $120,000 $100,000 $20,000 20% wages expense 50,000 40,000 10,000 25 supplies expense 2,000 1,700 300 15 which of the items is stated incorrectly? a. fees earned b. supplies expense c. none of these choices are correct. d. wages expense