Formula for 2 values of the same column

I have the "From" and "To " fields (in the detail section as in the attached jpeg attachment ) which are numeric and are from Table 1. However, the description to the numeric values are in a different table. How do I write a formula to get the description for both values in the detail section?(Is it necessary to add Table 2 using Database Expert?)

NOTE: [This is an existing report and adding any more tables may break other grouping already existing in the report.]

Any help/ guidance would be greatly appreciated. Thanks in advance.

Malini