The average pocket money of $3$ friends $A, B,$ and $C$ is $Rs. 80$ per month. If $B$ spends double and $C$ spends triple of what $A$ spends during that month,and if the average of their unspent pocket money is $Rs. 60,$ then how much does $A$ spend (in $Rs.$)?

The average marks of Sameer decreased by $1,$ when he replaced the subject in which he scored $40$ marks with two other subjects in which he scored $23$ and $25$ marks respectively. Later,he also included $57$ marks of Computer Science,and the average marks increased by $2.$ How many subjects were there initially?

The average weight of $5$ persons,sitting in a boat,is $38 \, kg$. If the average weight of the boat and the persons sitting in the boat is $52 \, kg$,what is the weight of the boat? (in $kg$)

The average age of a husband,wife,and their child $3 \text{ years}$ ago was $27 \text{ years}$,and the average age of the wife and the child $5 \text{ years}$ ago was $20 \text{ years}$. The present age of the husband is (in $\text{years}$):

$A, B, C$ and $D$ are four consecutive odd numbers and their average is $42$. What is the product of $B$ and $D$?

Eleven years earlier,the average age of a family of $4$ members was $28 \, \text{years}$. Now,the average age of the same family with $6$ members is still the same,even though $2$ children were born in this period. If they belong to the same parents and the age of the first child at the time of the birth of the younger child was the same as the total number of family members just after the birth of the youngest member,then what is the present age of the youngest member of the family in years?