Find a number A such that A% of 75 = 75% of A.
The answer is that A can be absolutely any number you like!
A general rule is that A% of B = B% of A.
Easy to see why. A% of B = (A × B)/100 and B% of A = (B × A)/100.
Sometimes this is a useful little result. For example, to find 40% of £75, change it to 75% of £40, which is easy, (because 75% is just three-quarters). So the result is £30.
Similarly, what's 17% of £50? Well it's the same as 50% of £17, which is half of £17 = £8.50.
Back to the book.
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