Ravi is $12$ years younger than Surya. Ravi's age is $40 \%$ of the sum of his and Surya's age. What will be Surya's age $9$ years hence?

The sum of two numbers is $\frac{23}{20}$ of the first number. The second number is what percent of the first?

In a college election between two candidates,one candidate got $55 \%$ of the total valid votes. $15 \%$ of the votes were invalid. If the total votes were $15,200$,what is the number of valid votes the other candidate got?

$A$ businessman imported laptops worth $Rs$ $210,000$,mobile phones worth $Rs$ $100,000$,and television sets worth $Rs$ $150,000$. He had to pay $10\%$ duty on laptops,$8\%$ on phones,and $5\%$ on television sets. How much total duty (in Rupees) did he have to pay on all items as per the above details?

In a History examination,the average for the entire class was $80$ marks. If $10 \%$ of the students scored $95$ marks and $20 \%$ scored $90$ marks,what was the average marks of the remaining students of the class?

In a motor of $120$ machine parts,$5 \%$ parts were defective. In another motor of $80$ machine parts,$10 \%$ parts were defective. For the two motors considered together,the percentage of defective machine parts was (in $\%$)