$P$ varies inversely with the product of $Q$ and $R$. When $Q = 6$ and $R = 12$,$P = 75$. When $Q = 5$ and $R = 10$,what is the value of $P$?

An amount of ₹ $1200$ is distributed among $A, B$ and $C$ in the ratio of $5: 7: 13$. What is the difference between the shares (in ₹) of $C$ and $B$?

₹ $600$ is divided among $A, B$ and $C$. If $\frac{2}{5}$ of $A$'s share plus ₹ $40$,$\frac{2}{7}$ of $B$'s share plus ₹ $20$,and $\frac{9}{17}$ of $C$'s share plus ₹ $10$ are all equal,then what is $A$'s share in ₹?

Ajay,Aman,Suman,and Geeta rented a house and agreed to share the rent as follows:
Ajay:Aman $= 8: 15$,Aman:Suman $= 5: 8$,and Suman:Geeta $= 4: 5$. The part of the rent paid by Suman will be

The fourth proportional to $0.2, 0.12$ and $0.3$ is

The ratio of three numbers is $2: 3: 5$. If the sum of the three numbers is $275$,then what is the largest among the three numbers?