a certain sum of money is to be shared among three brothers. one of them gets 2/5 of it, another gets 1/4 of it and the third one gets £2.10. how much is the sum of money

Answer 1

If the total is x, then we know that
2/5 x + 1/4 x + 2.10 = x
Now just solve for x

Answer 2

x - 2/5x - 1/4x = 2.1
x - 0.4x - 0.25x = 2.1
x - 0.65x = 2.1
0.35x = 2.1
x = 2.1/0.35