Mary needs school supplies. She has 6 classes and needs 1 folder for each class. She also needs 3 pencils for each class. She decides that for every 6 pencils she should have 1 eraser. She also needs a set of paints for an art class. Folders cost $6, pencils cost $2, and erasers cost $1. If she spends $80, how much did the set of paints cost in dollars? Give the rationale and then the answer.
Let's think step by step. Mary needs 6 * 1 = 6 folders. Mary needs 6 * 3 = 18 pencils. Mary needs 18 / 6 = 3 erasers. Mary spends 6 * 6 = $36 on folders. Mary spends 18 * 2 = $36 on pencils. Mary spends 3 * 1 = $3 on erasers. Mary spends 36 + 36 + 3 = $75 on all the supplies except the paints. Mary spends 80 - 75 = $5 on the paint set.. The answer is: 5.

Jessica is having a sweet tooth and bought 10 chocolate bars, 10 packs of gummy bears, and 20 bags of chocolate chips. Her total rang up to $150. If the cost of a pack of gummy bears is $2 and a bag of chocolate chips costs $5, how much does 1 chocolate bar cost? Give the rationale and then the answer.
Let's think step by step. The gummy bears cost 10 * 2 = $20. The chocolate chips cost 5 * 20 = $100. The total cost for these two is 100 + 20 = $120. The chocolate bars in total cost 150 - 120 = $30. A single chocolate bar costs 30 / 10 = $3.. The answer is: 3.

Two white socks cost 25 cents more than a single brown sock. If two white socks cost 45 cents, how much would you pay for 15 brown socks? Give the rationale and then the answer.
Let's think step by step. Two white socks cost 25 cents more than a single brown sock, meaning a brown sock is sold at $0.45 - $0.25 = $0.20. The cost of buying 15 brown socks is 15 * $0.20 = $3.. The answer is: 3.