In 50 gm alloy of gold and silver. the gold is 80% by weight. How much gold should be mixed to this alloy so that the weight of gold would become 95%?

Three vessels contain alcoholic solutions with the concentrations of alcohol as 0.25, 0.5 and 0.75 respectively. 4 litres from the first, 6 litres from the second and 8 litres from the third are mixed. What is the ratio of alcohol and water in the resultant mixture?