If the compound interest on a sum at the rate of 10% p.a. for 2 years is Rs. 105, then find simple interest of same amount for same year and same rate of interest.

110 100 120 130

100

C.I. @10%pa for 2 years = 21% S.I. @10%pa for 2 years = 20% ATQ, ⇒ P × 21% = 105 ⇒ P × 1% = \(\frac{105}{21}\) = 5 ⇒ P × 20% = 5 × 20 = 100