You should probably get some tropical fish flakes, but for the time being you can feed it goldfish flakes. There's probably some difference since the molly and the goldfish need to be in different temperatures. You should have them in separate tanks if you don't right now. Goldfish are cold water fish, and mollies are tropical. One temperature in the middle won't be sufficient because a lower temp to make the goldfish happy will stress the molly out, and the higher temperature to make the molly happy will stress the goldfish out.
You can keep them together temporarily, but I strongly suggest you get a separate tank (if you currently have them togeth). I can't tell from your post if your fish are together or not.
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