$6 \frac{1}{4} \%$ of $1600 + 12 \frac{1}{2} \%$ of $800$ equals

$5 \%$ of $(25 \%$ of $₹ 1600)$ is

$A$ person scores $45 \%$ of the total marks in the exam and still fails by $40$ marks. The passing percentage of the exam is $55 \%$. What is the maximum marks of the exam?

The value of a machine depreciates at the rate of $10 \%$ every year. It was purchased $3$ years ago. If its present value is $₹ 8748$,its purchase price was:

How many litres of pure acid are there in $8$ litres of a $20\%$ solution?

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?