50 students sat a history and geography test work out how many failed at least one test
To find the number of students who failed at least one test, we need to find the number of students who failed in history and geography separately. Then, we will subtract the number of students who passed both tests.
Let's say 'x' students failed the history test, and 'y' students failed the geography test. Since we want to find the number of students who failed at least one test, we will add 'x' and 'y'. But if we do so, the students who failed both tests will be counted twice. Therefore, we need to subtract the number of students who failed both tests.
Let's say 'z' students failed both the history and geography tests. So, the number of students who failed at least one test would be x + y - z.
Without knowing the actual values of x, y, and z, we cannot determine the exact number of students who failed at least one test.