Question: The difference in the number of pens that Alice and Clara each have matches their age difference. Alice has 60 pens and Clara has 2/5 times as many pens as Alice. If Alice's age is 20 and Clara is older than Alice, calculate Clara's age in 5 years to come.
Answer: If Alice has 60 pens, Clara 2 / 5 * 60 = 24 pens. The number of pens that Alice has more than Clara is 60 - 24 = 36. Since Alice is 20, and the number of pens that Alice has more than Clara is their age difference, Clara is 20 + 36 = 56 years old. In five years, Clara's age will be 56 + 5 = 61 years. The answer is 61.
[Question]In seven years, Talia will be 20 years old. Talia's mom is currently three times as old as Talia is today. In three years, Talia's father will be the same age as Talia's mom is today. Currently, how many years old is Talia's father?
[Answer]In seven years, Talia will be 20 years old, and therefore Talia is currently 20 - 7 = 13 years old. Talia's mom is currently three times as old as Talia is today, or 3 * 13 = 39 years old. If in three years, Talia's father will be the same age as Talia's mom is today, then Talia's father is currently 39 - 3 = 36 years old. The answer is 36.
Q: Teresa scored 70 marks in science, 80 in music, 85 in social studies, and the physics exam, which was the hardest test that Teresa had ever taken in her entire life, she scored half as many marks as she scored in music. Calculate the total marks Teresa scored in all the subjects.
A: The total marks of science and music are 70 + 80 = 150. When you add the marks she scored in social studies, the full marks become 150 + 85 = 235. She scored half as many marks in physics as she scored music, totaling 1 / 2 * 80 = 40 marks. When you add the marks she scored in physics to the total marks of the other subjects, the full marks become 235 + 40 = 275. The answer is 275.
Question: The grocery store sells chips for $2 per packet and corn chips for $1.5 per packet. John would like to buy 15 packets of chips, and with the rest of the money he has left, buy as many packets of corn chips as he can. How many packets of corn chips could John buy if he has $45 for his entire purchase?
Answer: John wants to buy 15 packets of chips, which will cost him 15 * 2 = $30. So John would have 45 - 30 = $15 left for the corn chips. John could buy for the rest of the money 15 / 1.5 = 10 packets of corn chips. The answer is 10.
[Question]Jessica’s class is going to a farm for a field trip. The school will bring all 35 students in the class plus 4 adult chaperones. The farm entrance fee for students costs $5 and $6 for adults. How much will the school pay for the farm entrance in all?
[Answer]The students' entrance fee cost $5 x 35 = $175. The adults' entrance fee cost $6 x 4 = $24. Therefore, the school will pay a total of $175 + $24 = $199 for the farm entrance. The answer is 199.
[Question]Kelsey turned 25 in 1999. Her older sister was born 3 years before Kelsey. It's currently 2021. How old is Kelsey's older sister?
[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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Kelsey turned 25 in 1999 so she was born in 1999 - 25 = 1974. Kelsey's sister is older by 3 years so she was born in 1974 - 3 = 1971. It's currently 2021 and Kelsey's sister was born in 1971 so she is 2021 - 1971 = 50 years old. The answer is 50.