We know that,
Simple Interest = prt/100
Where, P = principal, r = % rate of interest per annum, t = time period in years
Let the two parts of the sum divided be Rs. x and Rs. (1000 – x)
Let’s assume that, x is lent out at 10% per annum for 5 years and
(1000 – x) is lent out at 12.5% per annum for 4 years.
According to the question,
50x = 50000 – 50x
100x = 50000
x = 50000/100 = Rs. 500
Thus, sum lent on 12.5% interest= 1000 – 500 = Rs. 500