Correct Answer - Option 2 : 7 : 3

Ten years ago, let the age of mother and her son be 3x and x respectively

According to the question

(3x + 20)/(x + 20) = 2/1

⇒ 3x + 20 = 2x + 40

⇒ x = 20

Present age of mother = 3 × 20 + 10 = 70 years

Present age of her son = 1 × 20 + 10 = 30 years

∴ Present age ratio of mother to her son = 70 : 30 = 7 : 3