There are $1400$ students in the school. $25 \%$ of them wear spectacles and $\frac{2}{7}$ of those who wear spectacles are boys. How many girls in the school wear spectacles?

If Rs. $2800$ is $\frac{2}{7}$ of the value of a house,what is the total worth of the house (in Rs.)?

$A$ batsman scored $110$ runs which included $3$ boundaries and $8$ sixes. What per cent of his total score did he make by running between the wickets?

In the last financial year,a car company sold $41,800$ cars. In this year,the target is to sell $51,300$ cars. By what percent must the sale be increased?

An empty fuel tank of a car was filled with an ordinary type of petrol. When the tank was one-third empty,it was filled with high-speed petrol. Again,when the tank was one-third empty,it was filled with an ordinary type of petrol. Again,when the tank was one-third empty,it was filled with high-speed petrol. At this time,what was the percentage of high-speed petrol in the tank?

The number of students in a class is increased by $20 \%$ and the number now becomes $66$. Initially,the number was: