20/68 as a percentage is 29.41%. This number tells you that the fraction is just under a third of a whole. When you see 20 parts out of 68, you can think of it as about three out of ten.
The fraction 20/68 can be reduced to 10/34, and then to 5/17, but the size of the part stays the same. Whether you write it as a fraction or a percentage, it still represents the same portion of a whole.
In everyday use, the percentage form is often easier to understand quickly. If you need to compare this value to other percentages, you can see that it is less than 30% and more than 20%, giving you a clear sense of its size.