Why is sin(20) = sin(160) = -sin(200) = -sin(340)?

Eric drew a scale drawing of a country park. the scale he used was 1 inch = 2.5 yards. the picnic area is 80 yards wide in real life. how wide is the picnic area in the drawing ?

Agreeting card company can produce a box of cards for $7.50. if the initial investment by the company was $50,000, how many boxes of cards must be produced before the average cost per box falls to $10.50?

Regular price 75$ discount 25%sale price?