Amy needs to mail a CD to a friend. She uses 41.cent stamps and 5.cent stamps to pay $168 in postage. How many of each stamp did Amy use? In 41-cent stamps and how much in 5-cent stamps?

Which statement explains how you could use coordinate geometry to prove the opposite sides of a quadrilateral are congruent? a. use the slope formula to prove the slopes of the opposite sides are the same. b. use the slope formula to prove the slopes of the opposite sides are opposite reciprocals. c. use the distance formula to prove the lengths of the opposite sides are the same. d. use the distance formula to prove the midpoints of the opposite sides are the same.