A milkman buys some milk at 50Rs / ltr. He adds 1 / 5 water in milk and sells the mixture at 50Rs / ltr. Find out profit %? 

In 64 liter of pure alcohol, 20 liter of water is mixed and then $$ {1\over 4}{th}$$ of the mixture is taken out. When x liter of water is added again then ratio of water to that of the alcohol becomes 1:2. Find value of x?

How many grams of water should be mixed in 9 grams of shaving lotion having 50% alcohol content so that the alcohol content in the lotion becomes 30%?

50 grams of an alloy of gold and silver contains 80% gold by weight, how much more gold should be mixed in this metal so that the alloy contains 95% gold?

There is 40% sugar in 3 liters of sugar solution, what percentage of sugar will be in the new solution if one liter of water is added to this solution?

Rajesh purchased two different kinds of alcohol. In the first mixture, the ratio of alcohol to water is 4 : 5 and in second mixture it is 6 : 7. If he mixes the two given mixtures and makes a third mixture of 22 litres in which the ratio of alcohol to water is 5 : 6, the quantity of first mixture that is required to make 22 litres of the third kind of mixture is.

A vendor sells potatoes at a cost price, but he mixes some rotten potatoes and thereby gains 25%. The percentage of rotten potatoes in the mixture is? 

In an alloy, the ratio of copper and zinc is 7 : 6. If 1,450 gm. of zinc mixed with in 14 kg 300gm. of an alloy, then the ratio of copper and zinc will be