828.57%
Step-by-step explanation:
The amount of sugar
in the starting solution contributes to a 36% concentration, so we have

units of sugar in the solution.
Into this solution, Sharon wants to pour
liters of water to obtain a smaller concentration of sugar in the overall solution:

So Sharon needs to add
liters of water to the solution to get the desired concentration.
15, because of the Pythagorean triple 8, 15, 17.