20:1/5division problem

100. Dividing meand multiplying by the reciprocal, for example the recipricol of 1/2 is 2 and for 15 it is 1/15. Another example that is easier to understand is 20/2. When you multiply by the recipricol you have 20 x 1/2. Therefore 20 divided by 1/5 is 20 x 5, or 100