3. There was an equal amount of water in two barrels. The amount of water in the first barrel initially decreased by $10 \%$, and then increased by $10 \%$. The amount of water in the second barrel, on the contrary, initially increased by $10 \%$, and then decreased by $10 \%$. In which barrel did the amount of water become greater?
3. Let there initially be $x$ liters of water in each barrel, then in the first barrel, after all changes, there became $x \cdot 0.9 \cdot 1.1 = 0.99 x$ liters of water, and in the second $x \cdot 1.1 \cdot 0.9$ - which is also $0.99 x$ liters of water. Answer: equally.