Averages Questions

A student scores $85\%$ in an examination. The scores were $79$, $81$, $88$ and $94$ in $4$ subjects. Find the student's score in the $5\text{th}$ subject.

A family consists of two parents and three children. If the average age of the parents is $36$ years and that of the children is $10$ years, find the average age (in years) of the family.

$18$ articles were sold at an average price of $\text{Rs. }15$. The cost price of $12$ articles was $\text{Rs. }16$ each. Find the cost price of each of the remaining $6$ articles if there was no profit/loss in the transaction.