If simple interest on a certain sum of money for 4 years at 5% per annum is same as the simple interest on Rs. 560 for 10 years at the rate of 4% per annum then the sum of money is:

A.1190
B.1120
C.1210
D.1280
Answer: B

Explanation: 

Let the required sum of money be Rs. X.
Here R1 = 5%, T1 = 4 years, R2 = 4%, T2 = 10 years.
Given  X : 560 = 1 / R1T1 : 1 / R2T2 :
               = 1 / 5X4 : 1 / 4X10
X = 2 or, X = Rs. 1120.