Question 370860
You need to add a certain amount of water, which we'll call 'w', in order to dilute your mixture down to 50% alcohol.

You know that the current mixture is 32% water by subtracting 68% alcohol from 100%,where 100% represents the total mixture.

w(the unknown amount of water you need to add)
0.32w (the amount of water in the current mixture)

w + 0.32w = 0.50
w =0.50 - 0.32
w = 0.18

You will need to add 18% more water to the current mixture to get a mixture with 50% alcohol.