Using date from a field for "last updated" date

hello,

Using date from a field for "last updated" date

i want to use date(starting from second entry) from another column as the initial date for another column.

for example

starting date last date

4/5/21 7/5/21

7/5/21 9/5/21

9/5/21

here last date column is using second entry from starting date. i am new to crystal reports so please help me out.