If the numerator of a certain fractions increased by 100% and the denominator is increased by 200%; the new fraction thus formed is $4 \over 21$. What is the original fraction ?

The ratio of the ages of A and B seven years ago was 3 : 4 respectively. The ratio of their ages nine years from now will be 7 : 8 respectively. What is B's age at present ?

The perimeter of a square is thrice the perimeter of a rectange. If the perimeter of the square is 84 cm and the length of the rectangel is 8 cm, what is the difference between the breadth of the rectangle and the sidce of the square?

Perimeter of the square = 84 cm Perimeter of the rectangle = 28 cm Perimeter of the rectangle = 2(1 + b) or, 2(8 + b) = 28 cm or, b = 14 - 8 = 6 cm. Breadth of the rectangle = 6 cm Side of the square = $84 \over 4$ = 21 cm Difference = 21 - 6 = 15 cm

Perimeter of the rectangle = 42m 2(l + b) = 42m or, l + 8.5 = 21 m or, l = 12.5m Area of the rectangle = 12.5 $\times$ 8.5 = 106.25 sq.m. Area of the circle. = 106.25 sq.

4 women and 12 children together take four days to complete a piece of work. How many days will four children alone take to complete the piece of work if two women alone can complete the piece of work in 16 days?