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?

If $10 \%$ of $x = 20 \%$ of $y,$ then $x : y$ is equal to

In a college,$150$ students of $MBA$ are enrolled. The ratio of boys to girls is $7:8$. There are three disciplines in the college,namely,Marketing,$HR$,and Finance. In the Marketing discipline,there are $50\%$ girls of their total number and the boys are $40\%$ of their total number. In the $HR$ discipline,girls are $30\%$ of their total number while boys are $30\%$ of their total number. The Finance discipline has girls $20\%$ of their total number and the boys are $30\%$ of their total number. $7$ boys and $9$ girls are in the $HR$ and Marketing both. $6$ boys and $7$ girls are in the $HR$ and Finance both. $5$ boys and $8$ girls are in the Marketing and Finance both. $2$ boys and $3$ girls are enrolled in all the three disciplines. The ratio of boys to girls enrolled only in the $HR$ discipline is:

In an army selection process,the ratio of selected to unselected candidates was $4:1$. If $90$ less had applied and $20$ less were selected,the ratio of selected to unselected candidates would have been $5:1$. How many candidates had applied for the process?

Gold is $19$ times as heavy as water and copper is $9$ times as heavy as water. In what ratio should these be mixed to get an alloy $15$ times as heavy as water?

On the entire Earth,the ratio between land and water is $1:2$,and in the Northern Hemisphere,this ratio is $2:3$. What will be the ratio of land to water in the Southern Hemisphere?