how to convert a decimal into a fraction, let the decimal be 0.75

let it be 0.75/1 (every number is a fraction over 1)this can then be written as 75/100, this can then be simplified to 15/20 when both top and bottom are divided by 5. This is not yet the smallest form as it can be divided by 5 again which gives the final answer being 3/4.