What is 20 fifths meter in centimeters?

First put the 20 fifths metres into something a little more recognisable:

20 x 1/5 metres

This is also 20/5 metres

And as 20/5 = 4, 20 fifths metres = 4 metres.

In each metre, there are 100 centimetres,

so 4 metres to 100 centimetres = 4 x 100 = 400 centimetres

So 20 fifths metres is 400 centimetres