Part a: sydney made $18.50 selling lemonade, by the cup, at her yard sale. she sold each cup for $0.50 and received a $3 tip from a neighbor. write an equation to represent this situation. (4 points)

part b: daria made a profit of $21.00 selling lemonade. she sold her lemonade for $0.75 per cup, received a tip of $3 from a neighbor, but also had to buy each plastic cup she used for $0.10 per cup. write an equation to represent this situation. (4 points)