Question

A sum of money lent out at simple interest amounts to $Rs720$ after $2$ years and to$Rs1020$ after a further period of $5$ years. What is the sum?

Answer 1

Simple interest for$2$ years $=$ $Rs.720.$

Simple interest for $7$ years$=Rs.1020$

Simple interest for$5$ years$=Rs.1020–Rs.720=Rs.300.$

Simple interest for $2$years $=(\frac{300}{5})\times 2=Rs.120$

Principal $=720–120=Rs.600$

Hence, the sum is $Rs.600$.