To determine the number of 1/5 there are in 4, divide the 4 by 1/5.

`4 -: 1/5`

To divide them, express the 4 as a fraction.

`=4/1 -: 1/5`

To divide two fractions, flip the second fraction and change the operation from division to multiplication.

`=4/1 xx 5/1`

`=20/1`

`=20`

**Therefore, there are 20 fifths in four wholes.**