Tips & Tricks Given: Present age ratio = 7 ∶ 8 Ratio of age after 10 years = 9 ∶ 11 Concept: Subtract 10 years from their present age and equate with the ratio of age 10 years ago. Calculation: Let the present age of Mohit and Subham = 7x and 8x 10 years before, age of Mohit = 7x – 10 Age of Subham = 8x – 10 ∴ (7x – 10) ∶ (8x – 10) = 9 ∶ 11 ⇒ (7x – 10)/(8x – 10) = 9/11 Cross multiply; ⇒ 77x – 110 = 72x – 90 ⇒ 5x = 20 ⇒ x = 4 ∴ Present age of Mohit = 7x = 7 × 4 = 28 years ⇒ Present age of Subham = 8x = 8 × 4 = 32 years ∴ Sum of Their present age = 28 + 32 = 60 years