Let qa be the quantity demanded of good a, pa be the price of good a, pb be the price of good b, and m be income. let the demand equation be qa=86-5pa-4pb+2m. if we know that pa=6, pb=3, and m=30, then the approximate value of the cross-price elasticity of demand is:

Which of the following statements is (are) true? i. free entry to a perfectly competitive industry results in the industry's firms earning zero economic profit in the long run, except for the most efficient producers, who may earn economic rent. ii. in a perfectly competitive market, long-run equilibrium is characterized by lmc < p < latc. iii. if a competitive industry is in long-run equilibrium, a decrease in demand causes firms to earn negative profit because the market price will fall below average total cost.