Equivalent rations means that it is the same for all in the table, you are given 8 and 6 (written as 8:6 as a ratio) simply this to get 4:3. So to get the other answers, simply divide the number you are given by the corresponding value (top numbers by 4 and bottom numbers by 3)
Your table should look like this
angle fish: 4|8|24|20
tiger fish : 3|6|18|15
I try to explain the problem as well as give the answer so I hope this helps!