Thanks for the response.
If we have a table with 5 fields, like text1,text2,number1,number2,number3 and we have the values
text1 text2 number1 number2 number3
a b 1 2 3
c d 4 6 5
e f 7 8 9
then, if the user selects a and c from field 'text1', we should get (1-4) = -3 in field 'number1', (2-6) = -4 in field 'number2' and (3-5) = -2 in field 'number3'. Please let me know if you have any questions.