We know that in the aquarium there is 6 less yellow fish. We also know that they take up 40% of the aquarium. We know that the other 60% of the fish tank has to be green fish.
From this we can see that the percentage difference between yellow fish’s 40% and green fish’s 60% is 20% And we also know that green fish has 6 more fish than yellow. So we know that 20% is 6 fish. We can use this data to know workout how many fish green has. The answer has to be 18. Hope this helps and if you get stuck You can comment underneath this and I’ll assist you there :)