read table

i have to fetch belnr from bkpf table, and tax amount(fwste) from bset table.

if for a particular belnr suppose if this belnr 1700000000 has 5 line items in bset table than i need tax amount for all those 5 line items it means i need addition of that tax amount in output

for eg in bset table

belnr fwste lifnr curr

17000000000 0.00 0002300000 usd

2.00

0.00

4.00

in ouput i should get only subtotal has

1700000000 6.00 00023000000 usd

please help how to do its urgent

thanks in advance