A sum of Rs 8000 is divided into two parts. The simple interest on first part at the rate of 21% per annum is equal to the simple interest on second part at the rate of 35% per annum. What is the interest (in Rs) of each part?

Let sum invested for 21% = Rs. $$100x$$ and sum invested for 35% = Rs. $$(8000-100x)$$

Time period = 1 year

=> Simple interest = $$\frac{P\times R\times T}{100}$$

According to ques,

=> $$\frac{100x\times21\times1}{100}=\frac{(8000-100x)\times35\times1}{100}$$

=> $$21x=(80-x)\times35$$

=> $$21x=2800-35x$$

=> $$35x+21x=56x=2800$$

=> $$x=\frac{2800}{56}=50$$

$$\therefore$$ Interest for each part = $$\frac{100\times50\times21\times1}{100}$$

= Rs. $$1050$$

=> Ans - (A)