Question: Derek has $40. He spends $14 on lunch for himself, $11 for lunch for his dad, and $5 on more lunch for himself. His brother Dave has $50 and only spends $7 on lunch for his mom. How much more money does Dave have left than Derek?
Answer: Derek has 40 - 14 - 11 - 5 = 10 dollars left. Dave has 50 - 7 = 43 dollars left. Dave has 43 - 10 = 33 more dollars left than Derek. The answer is 33.

Question: Roy spends 2 hours on sports activities in school every day. He goes to school 5 days a week. If he missed 2 days within a week, how many hours did he spend on sports in school that week?
Answer: He goes to.school 5 days a week so if he misses 2 days within the week he was present for 5 - 2 = 3 days. He spends 2 hours every day for a total of 2 * 3 = 6 hours. The answer is 6.

Question: On a monthly basis, Esperanza pays $600 in rent, 3/5 as much money on food as she pays on rent and her mortgage bill costs three times the amount of money she spends on food. If she saves $2000 and also pays the equivalent of 2/5 of her savings in taxes, calculate her gross monthly salary.
Answer: Esperanza pays 3 / 5 * $600 = $360 on food. She also spends 3 * $360 = $1080 on mortgage bills. Her expenses in taxes amount to 2 / 5 * $2000 = $800. Esperanza's total monthly expenses are $800 on taxes + $1080 on mortgage bills + $360 on food + $600 on rent = $2840. Her gross salary is $2840 for expenses + $2000 on savings = $4840. The answer is 4840.

Question: There are 20 boys and 11 girls in the second grade and twice that number in the third grade. How many students are in grades 2 and 3?
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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There are 20 + 11 = 31 students in second grade. There are 31 x 2 = 62 students in third grade. In total, there are 31 + 62 = 93 students. The answer is 93.