$A$ person's present age is two-fifth of the age of his mother. After $8$ years,he will be one-half of the age of his mother. How old is the mother at present (in $years$)?

$15$ litres of mixture contains $20 \%$ alcohol and the rest water. If $3$ litres of water be mixed with it,the percentage of alcohol in the new mixture would be:

Before a war,the ratio of tanks to planes in an army was $5:3$. During the war,$1000$ tanks were destroyed and $800$ planes were destroyed. The ratio of tanks to planes became $2:1$. What is the number of tanks after the war?

The population of a town is $3,11,250$. The ratio between women and men is $43:40$. If there are $24\%$ literate among men and $8\%$ literate among women,the total number of literate persons in the town is:

Out of the number of qualified candidates from State $P$ in $2008,$ the respective ratio of male and female candidates is $11: 7.$ If the number of female qualified candidates from State $P$ in $2008$ is $126,$ what is the total number of qualified candidates (both male and female) from State $P$ in $2008?$

Three containers have volumes in the ratio $3:4:5$. They are full of mixtures of milk and water. The mixtures contain milk and water in the ratio of $4:1$,$3:1$,and $5:2$ respectively. The contents of all these three containers are poured into a fourth container. The ratio of milk and water in the fourth container is