Megan's demand for brownies is Q_d= 90 -4P.

1. Calculate the price elasticity as the price moves from P₀= 20 to P₁= 15 by using the mid-point price elasticity formula (hint: this is the same formula as the arc elasticity formula). _p=

1. Given the information, we calculate the total revenue (TR) at P = 20 and P = 15 separately. When P = 20, TR =$200; when P = 15,TR= $450. Does the total revenue (TR) increase, decrease, or stay the same when the price decreases from P = 20 to P= 15? Use your calculation of the price elasticity of demand at these two different prices to explain the result in the change of total revenue.