[Question]: For the school play, 40 rows of chairs were set up where there were 20 chairs in each row. If only 10 seats were not occupied, how many seats were taken?
[Answer]: The school prepared 40 x 20 = 800 chairs. So, 800 - 10 = 790 chairs were taken.
So the answer is 790.

[Question]: Mrs. Gable’s third grade class is on a field trip to the beach. For lunch, Mrs. Gable brought 20 lunches for the 20 students in her class. She included a pack of animal crackers in each lunch bag for dessert. Each pack of animal crackers contained 10 animal crackers. If 2 students did not eat their animal crackers, how many animal crackers were eaten in total among Mrs. Gable’s students?
[Answer]: Since 2 students did not eat their animal crackers, 20 - 2 = 18 students ate their animal crackers. The students ate a total of 18 * 10 = 180 animal crackers.
So the answer is 180.

[Question]: Big Dig Mining Company mines three different types of ore: copper, iron, and nickel. Across all their mines, 10% of their output is nickel, 60% is iron, and the rest is copper. They mine 720 tons of nickel a day. How many tons of copper does Big Dig Mining Company mine daily?
[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 R be the total ore output of the company. Of Big Dig’s output, 100 - 10 - 60 = 30% is nickel. Since 720 is 60% of 100% of their output, 720 / R = 60 / 100. Thus, Big Dig mines R = 100 * 720 / 60 = 1200 tons of ore daily. Therefore, Big Dig mines 1200 * 30 / 100 = 360 tons of copper daily.
So the answer is 360.