one fifth
Assuming that you mean "fifths", the answer is three fifths.
Subtracting one fifth from one gives 1 - 1/5 = 4/5, or four fifths.
One whole minus two fifths is three fifths.
one fifth
10 and 2/5
Call it 21 fifths minus 13 fifths, ie 8 fifths which is one-and-three-fifths
1 fifth
Four fifths.
16/5 - 14/5 = 2/5
1 and 4 fifths.
Fourteen and four fifths.