Let’s denote the volume of the solution by V.

According to the problem, the solution contains 8% acid. This means that in every 100 ml of the solution, there are 8 ml of acid.

We know that there are 15 ml of acid in the solution. Using the proportion method, we can set up the following equation:

8 ml acid / 100 ml solution = 15 ml acid / V ml solution

Cross-multiplying, we get:

8 ml acid x V ml solution = 100 ml solution x 15 ml acid

Simplifying, we get:

V ml solution = (100 ml solution x 15 ml acid) / 8 ml acid

V ml solution = 187.5 ml

Therefore, the volume of the solution is 187.5 ml.