Hey there!!
Let's take the amount of pounds as 'p'
The cost for each pound is $8.04
Total amount of money is $80
The amount of money left is $31.76
Total amount of money left = Total amount of money - money spent on the coffee.
... 31.76 = 80 - 8.04p
... -48.24 = -8.04p
... 6 = p
Hence, the total number of pounds taken is "6".
Hope it helps!