Choose a value x such that:
You begin with 3x, and round to the closest whole number.
Multiply this by 4x, and round to the closest whole number
Finally multiply this by 5x, and you will have the answer 273.
For example:
Let x = 7/4,
3x = 21/4 = 5.25, round to 5,
Multiply by 4x (7) = 35, round to 35.
Finally multiply by 5x (35/4) to get 306.25
As 306.25 is not 273, this is not the correct value of x. But what is?