Two numbers are in the ratio 5 : 8. If 10 is subtracted from each number, the ratio becomes 4 : 7. The numbers are :

1. 80 and 40

2. 50 and 80

3. 25 and 40

4. 40 and 25

The compounded ratio of x - y : x + y and (x + y)² : x² - y² is :

1. 2 : 1

2. 1 : (x + y)²

3. 1 : 1

4. 1 : 2

If $\dfrac{m + n}{m + 3n} = \dfrac{2}{3}$, find : $\dfrac{2n^2}{3m^2 + mn}$.

If the ratio of 8 and 11 is same as the ratio of 2x - y to x + 2y, find the value of $\dfrac{7x}{9y}$.