Aaron is giving his exam and after spending a lot of time answering the questions, he asks the examiner about the time that is left for the exam.
The the examiner is quite obtuse with her answer and says that the amount of time left is 1/5th of the time that has already passed.
Can you find out the amount of time left if the total time was 90 minutes?
15 minutes are left.
One fifth of 75 is 15 and they both add up to 90 minutes, which confirms that the answer is correct.