If $0.75 : x :: 5 : 8,$ then $x$ 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: Marketing,$HR$,and Finance. In the Marketing discipline,there are $50\%$ of the total girls and $40\%$ of the total boys. In the $HR$ discipline,there are $30\%$ of the total girls and $30\%$ of the total boys. In the Finance discipline,there are $20\%$ of the total girls and $30\%$ of the total boys. $7$ boys and $9$ girls are in both $HR$ and Marketing. $6$ boys and $7$ girls are in both $HR$ and Finance. $5$ boys and $8$ girls are in both Marketing and Finance. $2$ boys and $3$ girls are enrolled in all three disciplines. What is the ratio of boys to girls only in the Marketing discipline?

The ratio of the present ages of Sita and Gita is $4:3$. If $4$ years ago,the ratio of their ages was $2:1$,the present age of Sita is (in years):

If $Rs. 782$ is divided into three parts proportional to $\frac{1}{2}: \frac{2}{3}: \frac{3}{4}$,then the first part is (in $Rs.$):

What should be subtracted from each term of the ratio $19: 23$ to make it equal to the ratio $3: 4$?

If $(x+y):(x-y)=11:1$,find the value of $\frac{(5x+3y)}{(x-2y)}$.