Tom decides to take 10 dance lessons that cost $10 each, but he gets two of them for free. How much does he pay? Give the rationale and then the answer.
Let's think step by step. He paid for 10 - 2 = 8 lessons. That means he pays 8 * $10 = $80.. The answer is: 80.

Christopher uses 1 packet of a sugar substitute in his coffee. He has 2 coffees a day. The packets come 30 to a box and cost $4.00 a box. How much will it cost him to have enough sugar substitutes to last him 90 days? Give the rationale and then the answer.
Let's think step by step. He uses 1 packet per cup of coffee and he has 2 cups a day so that's 1 * 2 = 2 packets. He wants enough to last him 90 days and he uses 2 packets a day so that's 90 * 2 = 180 packets. The packets come 30 to a box and he needs 180 packets so that's 180 / 30 = 6 boxes of sugar substitute. Each box costs $4.00 and he needs 6 boxes so that's 4 * 6 = $24.00.. The answer is: 24.

Darlene's car gets 20 miles/gallon. Martha's car gets half as many miles per gallon as Darlene’s car. How many gallons does Martha’s car require to make a 300-mile trip? Give the rationale and then the answer.
Let's think step by step. Martha’s car gets 20 / 2 = 10 miles per gallon. Total gallons Martha’s car requires is 300 / 10 = 30 gallons.. The answer is: 30.