The average salary of the entire staff in an office is $Rs.\, 500$ per day. The average salary of officers is $Rs.\, 750$ and that of non-officers is $Rs. \,$ $250 .$ If the number of officers is $15,$ then find the number of nonofficers in the office?

Find the average of all the numbers between $6$ and $34$ which are divisible by $5$

The average age of a cricket team reduces by $2$ when two senior players aged $32$ and $30$ are replaced by $2$ youngsters of equal age. What is the age of these players?

The cost of $5 \,kg$ of apples is $Rs.\, 450 .$ The cost of $12$ dozen mangoes is $Rs.\, 4320$, and the cost of $4 \,kg$ of oranges is $Rs.\,240.$ What is the total cost of $8 \,kg$ of apples$, 8$ dozens of mangoes and $8 \,kg$ of oranges ? (in $Rs.$)

The average weight of $A, B$ and $C$ is $84 \,kgs.$ If $D$ joins, the average weight now is $80 \,kgs$. If another person $E$ who is $3\, kgs$ heavier than $D$ replaces $A$ then the average weight of $B, C, D$ and $E$ becomes $79\, kgs.$ what is the weight of $A $ in $kg$ ?

The average of five numbers is $27 .$ If one number is excluded, the average becomes $25 .$ The excluded number is