The ratio between two given numbers is 9 : 7. If each number is increased by 6, then the ratio becomes 21 : 17. What is the difference between the two given numbers?

8

A : B

9 : 7

After increasing both numbers by 6, the ratio becomes,

A : B

21 : 17

To compare both of them, we multiply initial ratio with 2,

(9 : 7) x 2= 18 : 14

⇒ Difference between final and initial a = 21 - 18 = 3 units = 6

⇒ 1 unit = 2,

⇒ The difference between the two given numbers = 21 - 17 = 4 x 2 = 8.