The ratio of acid and water in three solutions is 1 ∶ 2, 5 ∶ 1 and 7 ∶ 2, respectively. These solutions are mixed in the ratio 1 ∶ 2 ∶ 3. In 540 ml of the resulting solution 45 ml water is mixed. The percentage of acid in the final solution is:
1
\(66 \frac{2}{3} \%\)
2
50%
3
60%
4
\(33 \frac{1}{3} \%\)