3. (3 points) Pour water from a cup full of water into an empty can. If 2 cups of water are poured in, the can with water weighs 0.6 kilograms; if 5 cups of water are poured in, the can with water weighs 0.975 kilograms. The empty can weighs $\qquad$ kilograms.
【Answer】Solution: The weight of 3 cups of water is: $0.975-0.6=0.375$ (kg), the weight of 2 cups of water is: $0.375 \div 3 \times 2=0.25$ (kg), the weight of the empty can is: $0.6-0.25=0.35$ (kg); Answer: The empty can weighs 0.35 kg.