A borrows Rs.800 at the rate of 12% per annum simple interest and B borrows Rs.910 at the rate of 10% per annum, simple interest. In how many years will their amounts of debt be equal? (1) 18 years (2) 20 years (3) 22 years (4) 24 year

Answer: (3)

Let us consider after t year amount is equal.

Consider an equation.

⇒ 800 + 96t = 910 + 91t

⇒ 5t = 110

⇒ t = 22 years

∴ After 22 years the amount will be equal.