Explain simply why 180 is the correct answer to: Max was doing homework in three different subjects. It took him 20 minutes to finish tasks from biology and two times more time to finish history. Geography took him the most time, three times more than history. How much time did Max spend on doing his homework?. Explanation:
Max finished history in 20 * 2 = 40 minutes. Finishing geography took the most time, which is 40 * 3 = 120 minutes. In total, for all three subjects, Max needed 20 + 40 + 120 = 180 minutes.