You can't because the number settings are applied to all the values of the same measure (your column in this case)
An alternative approach could be to create different measures (one for each value of repair type) with a Filter statement.
You could then create two measures "Irreparable %' and 'NFF %'.
With all the measures clearly defined in the criteria tab you could set a different data format for the two percentages
This might be slightly different but it could help with visualizing how to reference data in a specific row and use it in a calculation: