Q. In adult Population or a city, 40% men and 30% women are married. What is the percentage of married adult population if no man marries more than one woman and no woman marries more than one man; and there are no widows and widowers?

Explanation : 

Married Adult Population

Let men population be = 100.

So no of married men are = 40.

Definitely no of married women will be 40 also.

30 women are married in 100. So 40 are married in 100 x 40/30 = 400/3 women population.

Now total population = 100 + 400/3 = 700/3.

Total married population = 40 + 40 = 80.

%age of married population = 80*3*100/700 = 34.28.