Option (c) is correct.

Ages of two sisters A and B = 7:6

So, A = 7x

B = 6x

After 12 years, their ages will be

A = 7x + 12

B = 6x + 12

So, (7x+12)/(6x+12) = 9/8

56x + 96 = 54x + 108

2x = 12

x = 6

Hence, difference between their ages

= 7x – 6x = x = 6 years.

विकल्प (c) सही है।

दो बहनों A और B की आयु = 7:6

अतः, A = 7x

B = 6x

12 वर्षों के बाद, उनकी आयु क्या होगी?

A = 7x + 12

B = 6x + 12

तो, (7x+12)/(6x+12) = 9/8

56x + 96 = 54x + 108

2x = 12

x = 6

इसलिए, उनकी उम्र के बीच का अंतर

= 7x – 6x = x = 6 वर्ष।