The question is:
In a class there are 9 people absent. This is 20% of the class
How many are there in the class when no-one is off ill?
so to work out i did: 1.8*9=16.2
but 10% of the question is 4.5 and 4.5*10= 45 (Half of 20 is 10 and half of 9 is 4.5)
so i recon 45 is the answer but how do I work it out the first way?