You can easily keep simplifying this fraction by 2 until you can't simplify it anymore, because they're both even.
\(\frac{28}{36} = \frac{14}{18} = \frac{7}{9}\)
It can be faster this way for most people, but you can also just find what number goes into both numbers evenly.
4 goes into both numbers.
\(28\div4=7\\36\div4=9\\\\ \frac{7}{9}\)
