Which expression is equivalent to 18 1/5 -(- 22 2/5)- (- 40 1/5)

The manufacturer of a new product developed the following expression to predict the monthly profit, in thousands of dollars, from sales of the productwhen it is sold at a unit price of x dollars.-0.5x^2 + 22x - 224what is represented by the zero(s) of the expression? a.the profit when the unit price is equal to 0b.the unit price(s) when the profit is equal to 0c.the profit when the unit price is greatestd.the unit price(s) when profit is greatest

Pls brainliest will be awarded if answer is correct

To prove a polygon is a rectangle, which of the properties listed must be included in the proof?