Acid in Water or Water in Acid - What is corect and why?

Two solutions of acid and water containing acid and water in the ratio 2 : 7 and 4 : 5, respectively are mixed in the ratio 2 : 5. What is the ratio of acid and water in the resulting solution?

Two vessels A and B contain solution of acid and water. In A and B the ratio of acid and water are 7 : 3 and 4 : 1, respectively. They are mixed in the ratio 1 : 2. What is the ratio of acid and water in the resulting solution?

Chlorine heptoxide was was dissolved in water. As a result an acid was obtained. Name the acid formed?