arithmetic
posted by Imran Qureshi .
a guy bought some fish from a farm.during 1st week 1/8 of fish died ,in next 2 weeks 3/5 of the remaining died.what fraction of the original fish died in last three weeks

i need to know the procedure and formula in detail ty

After the first 1/8 died, only 7/8 were left
3/5 of those died, meaning 3/5 * 7/8 of the original number died
1/8 = 5/40
3/5 * 7/8 = 21/40
So, 26/40 = 13/20 of the fish died 
Never buy fish from a farm. Farmed fish is yuucky. Good fish comes from the ocean.
lets start with 40 fish
the first week 5 die so we have 35 which is 7/8 of original
after first week 7/8 or 35 remain
then in weeks two and three 3/5* 35 = 21 die so we are left with 35 21 = 14 fish
so in those first three weeks 26 died
26/40 = 13/20 
ty