If $0.75 : x :: 5 : 8,$ then $x$ is equal to

An alloy of copper and zinc is taken in the ratio $1: 2$,and another alloy of the same metals is taken in the ratio of $2: 3$. How many parts of the two alloys must be taken to obtain a new alloy consisting of copper and zinc that are in the ratio $3: 5$?

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. What percentage of students are enrolled in all three disciplines?

$A, B, C$ and $D$ purchase a gift worth $Rs. 60$. $A$ pays $\frac{1}{2}$ of what others are paying,$B$ pays $\frac{1}{3}$ of what others are paying,and $C$ pays $\frac{1}{4}$ of what others are paying. What is the amount paid by $D$?

$A$ sum of ₹ $1,300$ is divided amongst $P, Q, R$ and $S$ such that $\frac{P \text{'s share}}{Q \text{'s share}} = \frac{Q \text{'s share}}{R \text{'s share}} = \frac{R \text{'s share}}{S \text{'s share}} = \frac{2}{3}$. Then $P$'s share is (in ₹):

Two horses cost as much as $5$ dogs,$6$ dogs as much as $8$ oxen,$10$ oxen as much as $50$ sheep,$14$ sheep as much as $9$ goats. If the price of one goat is $Rs. 700$,find the cost of one horse (in $Rs.$).