A company that provides whale-watching tours takes groups of 21 people at a time. The company'srevenue is 80 dollars per adult and 60 dollars perchild. If the company's revenue for one group consisting of adults and children was 1,440 dollars,how many people in the group were children?

Explanation

To solve this problem, let x be the number of adults and y be the number of children. The total number of people is 21, so x + y = 21. The revenue equation is 80x + 60y = 1440. Substitute x = 21 - y into the revenue equation: 80(21 - y) + 60y = 1440. Simplify to get: 1680 - 80y + 60y = 1440. Combine like terms to get -20y = -240, then divide both sides by -20 to find y = 12. Therefore, there are 12 children.Other options are incorrect as they do not satisfy both the total number of people and the revenue equations simultaneously.