1. **Stating the problem:** Andi has an aquarium of size 60 cm x 45 cm x 45 cm. There are 5 goldfish, 8 comet fish, and 3 molly fish. Each goldfish and molly fish needs a minimum space of 15 cm x 15 cm x 15 cm. Two comet fish together need the same space as one goldfish or molly fish. We want to find how many more comet fish can be added to fill the aquarium maximally. 2. **Calculate the total volume of the aquarium:** $$V_{aquarium} = 60 \times 45 \times 45 = 121500 \text{ cm}^3$$ 3. **Calculate the volume needed per goldfish or molly fish:** $$V_{fish} = 15 \times 15 \times 15 = 3375 \text{ cm}^3$$ 4. **Calculate the volume needed per comet fish:** Two comet fish need the same volume as one goldfish or molly fish, so one comet fish needs half that volume: $$V_{comet} = \frac{3375}{2} = 1687.5 \text{ cm}^3$$ 5. **Calculate the total volume occupied by existing fish:** Goldfish and molly fish total: $$5 + 3 = 8 \text{ fish}$$ Volume for these 8 fish: $$8 \times 3375 = 27000 \text{ cm}^3$$ Comet fish total: $$8 \text{ fish}$$ Volume for these 8 comet fish: $$8 \times 1687.5 = 13500 \text{ cm}^3$$ Total volume occupied: $$27000 + 13500 = 40500 \text{ cm}^3$$ 6. **Calculate remaining volume in aquarium:** $$121500 - 40500 = 81000 \text{ cm}^3$$ 7. **Calculate how many more comet fish can fit in remaining volume:** Each comet fish needs 1687.5 cm³, so: $$\text{additional comet fish} = \left\lfloor \frac{81000}{1687.5} \right\rfloor = 48$$ **Final answer:** Andi can add **48** more comet fish to fill the aquarium maximally.