The average age of $6$ members of a family is $20$ years. If the age of a servant is included,the average age increases by $25\%$. What is the age (in years) of the servant?

There were $35$ students in a hostel. If the number of students is increased by $7$,the expenditure on food increases by $Rs. \,42$ per day,while the average expenditure per student is reduced by $Rs. \,1$. What was the initial total expenditure on food per day? (in $Rs.$)

$A$ student bought $4$ books for $Rs. 120$ from one book shop and $6$ books for $Rs. 150$ from another. The average price (in rupees),he paid per book was

The average age of Seema,Sapna,Asha,Kavita,and Atrye is $40 \text{ years}$. The average age of Seema and Sapna is $35 \text{ years}$,and the average age of Asha and Kavita is $42 \text{ years}$. What is the age of Atrye?

The average salary,per head,of all the workers of an institution is $Rs.\, 60$. The average salary of $12$ officers is $Rs.\, 400$; the average salary,per head,of the rest is $Rs.\, 56$. The total number of workers in the institution is:

Of the three numbers,the second is twice the first and is also thrice the third. If the average of the three numbers is $44,$ the largest number is