The sports boosters club is having a bake sale to buy uniforms. They want to raise $250. They need to rent a booth for $20. How many dozen cookies will they need to sell if they charge $3 per dozen?
 Which equation could be used to solve this problem?
 1. 250 = 3c - 20
 2. 250 = 3 - 20c
 3. 250 = 20 - 3c
 4. 250 = 20c - 3