$A$ speaks truth in $80 \%$ of the cases and $B$ in $90 \%$ of the cases. Find the percentage when they contradict each other in describing the same facts. (in $\%$)

If the income of $R$ is $30 \%$ more than the income of $Q$ and the income of $Q$ is $20 \%$ more than the income of $P$,then the income of $R$ is how much percent more than the income of $P$ (in $\%$)?

The difference between two numbers is $1600$. If $7.5\%$ of one number is equal to $12.5\%$ of the other number,find the two numbers.

For admission in a postgraduate program of Calcutta University,$90 \%$ of the candidates who appeared for the written test were males and the rest were females. $60 \%$ of the males and $80 \%$ of the females passed the written test. What is the total number of students who appeared for the written test,if the total number of passed candidates was $1240$?

$A$ set $A$ consists of integers $27, 28, 30, 32$ and $33$. If an integer $K$ is included,the average of set $A$ will increase by $30\%$. What is the value of integer $K$?

In Jamshedpur,only two newspapers,Dainik Jagran and Prabhat Khabar,are published. It is known that $25 \%$ of the city population reads Dainik Jagran and $20 \%$ reads Prabhat Khabar,while $8 \%$ reads both the newspapers. It is also known that $30 \%$ of those who read Dainik Jagran but not Prabhat Khabar look into advertisements,$40 \%$ of those who read Prabhat Khabar but not Dainik Jagran look into advertisements,and $50 \%$ of those who read both the newspapers look into advertisements. What is the percentage of the population who read an advertisement?