5) In a maths class the ratio of pupils that had done their homework to those that had not is 5:4. 15 pupils had done their homework. The teacher said they would collect the
homework the next day. The next day, the ratio of those who had done it to those that
had not was 2:1.
The teacher said that only 3 more pupils had done their homework. Could the teacher
be correct?
You must show all of your working.