Question 4304
We know that 20.4 is 24% of an unknown number.  
1.)  Convert the fraction (24%) into a decimal.  That will give you .24

2.)  If you think about it, you can write out the problem just like it sounds:

20.4 is equal to .24 of (x)
20.4=.24(x)

3.)  Multiply both sides by {{{(1/.24)}}}
{{{20.4/.24}}}={{{(.24x)/.24}}}

4.)  Get rid of the decimals by moving two spaces to the right (multiply by 100)
{{{2040/24}}}={{{(24x)24}}}

5) Reduce to get your answer!
85=x

So 20.4 is 24% of 85.