Glen Distilliries is famous for their Whiskeys which contain 50% alcohol. The blending department has received three casks of distilled liquor, the first cask containing four gallons of 45% alcohol, the second cask containing five gallons of 48% alcohol and the third cask containing one gallon of x% alcohol. The master blender takes y/z gallons of liquor from the third cask and adds it to the first cask. The remaining liquor from the third cask is added to the second cask. The first and second casks now contain Whiskey with 50% alcohol each. If y and z are relatively prime natural numbers, what is the value of x + y + z?