Create field in crystal report which is result of division of two other fields from the dataset

Hi,

I have two tables in dataset from which I fill the dataset. I create a crystall report from it. Now I want to have one field which is not in either table of the dataset and its value to be result of the division of one field from the first table and one filed from the second table.

Could anybody help me please how to create a field in the crystall report which is the result of the division of two other fields in the dataset?

For example I have a field table1.field1 and table2.field2 and I want to create field

Prospotr=table1.field1/table2.field2

Thanks