The equation y = 32.92-572.87 can be used to model the relationship between sales at a local ice cream shop, y, in dollars, and the outside temperature, a, in degrees Fahrenheit (F).

Complete the statements.
a. When the outside temperature is 30°F, the sales are estimated to be ____.
b. When the outside temperature is ____, the sales are estimated to be $1, 993.33.