Answer: 3/100
3% is equivalent to 3/100.
It can be read as 3 out of 100 percent. The line ends here and we can't simplify it any further.
Unfortunately, 100 is not a multiple of 3. The multiple of three that is closest to 100 is 99. However, that is the closest we can get to 100 without going over. The next multiple would be 102, which is over 100.
For these reasons, the simplest fraction equal to 3% is 3/100.