How do you write $20 \%$ as a fraction?

Hint:
This is a problem in which the student has to bring the percentage into a fraction in its simplest form. This can be treated as a problem in fraction in which the first step would be to convert percentage into a fraction by dividing it by $100$ . And then the student can bring both the numbers in its simplest form.

Complete step by step solution:
Recall that "percent" means "per hundred".
Therefore, we can write that $20%=\dfrac{20}{100}$
Next, try to reduce the fraction.
Since the greatest common divisor of the numerator and the denominator equals $20$, we can write that
Therefore, \[\dfrac{20\div 20}{100\div 20}=\dfrac{1}{5}\] .

Hence, $20 \% = \dfrac{1}{5}$.

Note:
Only important step in this sum is to first bring the percentage into a fraction and then in terms of its prime factors. Sometimes when the complicated sum like $20%\times \dfrac{5}{20}$ , it is advisable that the student first converts all the terms into the form of a fraction and then cancels out common terms after which, he/she should reduce the remaining terms to its prime factors.