Ethanol fermentation and distillation question(a good one)?

If i let a mixture of 70 ml water/moles react( along with the yeist , ect), then run a couple of distillations, how can I find the concentration of ethanol in the reaction mixture before i distill it? With the following info. The density of the Distilled product has a density of 0.875719 g/ml and is about 67.5% ethanol bu weight and 75% by volume.