A certain sum is invested at simple interest at 14% p.a. for two years instead of investing at 12% p.a. for the same time period. Therefore the interest received is more by Rs. 840. Find the sum?  Choices:
A) s. 7000 B) s. 9000 C) s. 14000 D) s. 17000 E) s. 42000
Let the sum be Rs. x.   (x * 14 * 2)/100 - (x * 12 * 2)/100 = 840   =&gt; 28x/100 - 24x/100 =840   =&gt; 4x/100 = 840   =&gt; x = 42000.   ANSWs. 42000R:s. 42000
<result>E</result>
A certain sum is invested at simple interest at 14% p.a. for two years instead of investing at 12% p.a. for the same time period. Therefore the interest received is more by Rs. 840. Find the sum?