Tire repair for each tire costs $7, plus another 50 cents for sales tax. If Juan needs all 4 tires repaired, how much is the final cost? Give the rationale and then the answer.
Let's think step by step. Juan pays 4 * 7 = 28 dollars for all four tire repairs. Juan pays 0.50 * 4 = 2 dollars in sales tax for all four tire repairs. Juan pays a total of 28 + 2 = 30 dollars.. The answer is: 30.

Jolene and Phil have four children, each with the same birthday. They gave birth to their first child exactly 15 years ago. They gave birth to their second child exactly one year after the birth of their first child. They gave birth to their third child on the fourth birthday of their second child. Two years after the birth of their third child, they gave birth to their fourth child. How old, in years, is their fourth child? Give the rationale and then the answer.
Let's think step by step. Their 1st child was born 15 years ago, and therefore is 15 years old. Their 2nd child was born 1 year after their 15 - year - old child, and therefore is 15 - 1 = 14 years old. Their 3rd child was born 4 years after their 14 - year - old child, and therefore is 14 - 4 = 10 years old. Their 4th child was born 2 years after their 10 - year - old child, and therefore is 10 - 2 = 8 years old.. The answer is: 8.

Marly has ten $20 bills, eight $10 bills, and four $5 bills. If she wants to change her bills to $100 bills, how many pieces of $100 bills will she have? Give the rationale and then the answer.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
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Let's think step by step. The ten $20 bills amount to $20 x 10 = $200. The eight $10 bills amount to $10 x 8 = $80. The four $5 bills amount to $5 x 4 = $20. So, Marly has a total of $200 + $80 + $20 = $300. Therefore, she will have $300 / $100 = 3 pieces of $100 bills.. The answer is: 3.