I assume you mean how to turn a repeating fraction like 0.99 repeating into a fraction?

Inorder to turn a repeating decimal into a fracation:

x = 0.99

10x = 9.99 i only multipplied x by 10^1 because the pattern is one long. if the decimal was something like 1.27272727, and repeats every two, do 10^2

10x-x = 9.99-0.99 this cancles out the repeating part of the fraction

9x = 9

x = 1/1

This is also a proof to why 0.99 repeating = 1.

Assuming youre asking how to simplify a fraction (idk you never know ig), simply find all the prime factors of the numerator and denominator.

For 2/4 it is 2/2*2. Then factor it out. 2/2*2 = 1/2.