Anul took a certain amount on a loan from the bank at 15% simple interest. He invests the amount in two halves at interest rates of 10% and 20% compounded annually. Anul takes his investments out after two years and pays back the bank's principal amount and interest. Investing the remaining amount at 20% compound interest rate (annually). What would be Anul's net profit percentage after 3 years since he first borrowed the amount from the bank?

Let's take the amount borrowed by Anul to be 100

The interest paid by Anul to the back would be $$\frac{100\times\ 15\times\ 2}{100}=30$$, hence net amount paid back to the bank: 130

His 50 invested at 10% compound interest would turn to $$50\left(1.1\right)^2$$, and the 50 invested at 12% compound interest would turn to $$50\left(1.2\right)^2$$

Giving the final amount with him to be $$50\left[\left(1.1\right)^2+\left(1.2\right)^2\right]=50\left[1.21+1.44\right]=50\left(2.65\right)$$

Giving the net amount with Anul at the end of two years to be 132.5

This gives a net profit of 2.5 after paying back the amount of 130 with interest to the bank. 

Investing this money at 20% interest rate for one more year, Anuwl would have a total of $$2.5\times\ 1.2\ =\ 3$$

Hence 3% profit.