Percentage denoted by the sign '%' means into hundred. So a percentage is any number as multiplied by hundred.

Hence 0.1 would be 1% as:

0.1*100=1

OR

1/100=0.1

In our case 5/7 as a percentage would be:

5/7*100

Multiplying:

500/7

Or

71.42

So 5/7 is 71.42%

Hence 0.1 would be 1% as:

0.1*100=1

OR

1/100=0.1

In our case 5/7 as a percentage would be:

5/7*100

Multiplying:

500/7

Or

71.42

So 5/7 is 71.42%