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

The average age of a man and his two twin sons,born on the same day,is $30 \, \text{years}$. The ratio of the ages of the father and one son is $5:2$. What is the father's age in $\text{years}$?

The average of six numbers is $32$. If each of the first three numbers is increased by $2$ and each of the remaining three numbers is decreased by $4$,then the new average is?

In an entrance examination,Ritu scored $56$ percent marks,Smita scored $92$ percent marks,and Rina scored $634$ marks. The maximum marks of the examination is $875$. What is the average marks scored by all the three girls together?

The average age of $24$ boys and their teacher is $15 \text{ years}$. When the teacher's age is excluded,the average age decreases by $1 \text{ year}$. What is the age of the teacher in years?

The average temperature for Monday,Tuesday,Wednesday and Thursday was $48^{\circ}$. The average temperature for Tuesday,Wednesday,Thursday and Friday was $52^{\circ}$. If the temperature on Monday was $42^{\circ}$,then the temperature on Friday was (in $degrees$):