The simple interest on a sum of money for 2 years at 12% per annum is ?1380. Find

(1) the sum of money
(2) the compound interest on this sum for one year payable half- yearly at the same rate.

This is in my course ...

Dear Student, 

   We have time = 2 years    Rate of Interest = 12%   and   Simple Interest = 1380
  So, 

    Principal = $\frac{S.I. \times 100}{R\times T}$
                  $$\begin{gathered} =\frac{1380\times 100}{12\times 2} \\ = 115\times 50 \\ = 5750 \end{gathered}$$

So, the Principal Amount is Rs 5750.

Now, Amount  = $P(1+\frac{R}{100}{)}^T$
               $$\begin{gathered} = 5750\times (1+\frac{6}{100}{)}^2 \\ = 5750\times (\frac{106}{100})\times (\frac{106}{100}) \\ = 5750\times \frac{11236}{10000} \\ = 6460.7 \end{gathered}$$

So, the Compound Interest is (6460.7 - 5750) = Rs 710.7

Hope this information clears your doubts.

Regards