Assuming "fith" is meant to be fifth, the answer is 100.
one fifth of 100 coins is 100X1/5= 20
one fifth as long as 500
One fifth 100 pence = 1 pound 100 / 20 = 5
It is: 1/5 of 100 = 20
100/5 = 20
the percentage of one-fifth = 20%1/5 * 100% = 100%/5 = 20%
20
20
100
10
One fifth. 1/520 of 100 = 2,00020% of 100 = 20