Lizzy: There are five times as many swordfish as pufferfish in an aquarium exhibit. If there are 90 fish total, how many pufferfish are there?.
Me: Hmmm, let me think. I think this is the detailed solution:
Let s be the number of swordfish and p be the number of pufferfish. We know that s = 5p and s + p = 90. Substituting the first equation into the second equation, we get 5p + p = 90. Combining like terms, we get 6p = 90. Dividing both sides by 6, we get p = 15. Final answer: 15.