It is strange that both meets did mistakes :)
Here's Your formula
However, do not suggest to translate into a percentage, Express fractions and to percent:
Right-click on the cell > Format cells... > Number > number formats: Percentage and set the required number of digits after the decimal point. So it will be easier to work with such numbers.
In order to learn enough to read any textbook on akselu for dummies or just the Excel help. office.microsoft.com/ru-ru/novice/FX101820736.aspx