Five years ago, the average age of $P$ and $Q$ was $15 \,year.$ Now, average age of $P , Q$ and $R$ is $20 \,year.$ What whould be the age of $R$ after $10$ $year$ in $year$ ?

An aeroplane travels $2500 \,km , 1200 \,km$ and $500\,km$ at $500\, km / h \,, 400 \,km $ and $250\,km / h $ respectively. The average speed is:(in $km/h$)

The average of six numbers is $20 .$ If one number is removed, the average becomes $15 .$ What is the number removed ?

The average score of Rahul, Manish and Suresh is $63.$ Rahul's score is $15$ less than Ajay and $10$ more than Manish. If Ajay scored $30$ marks more than the average score of Rahul, Manish and Suresh, what is the sum of Manish's and Suresh's scores ?

The average of $X_{1}, X_{2}$ and $X_{3}$ is $14 .$ Twice the sum of $X_{2}$ and $X_{3}$ is $30 .$ What is the value of $X_{1} ?$

A cricketer whose bowling average is $12.4$ runs per wicket takes $5$ wickets for $26$ runs and thereby decreases his average by $0.4$ The number of wickets taken by him till the last match was