A sum of ₹10000 is invested in three schemes of simple interest. The annual interest rates are respectively, 4%, 6% and 10%. ₹4000 were invested in the first scheme. If the total interest earned after five years is ₹2800, then how much money was invested in the third scheme?

The annual interest rates are respectively, 4%, 6% and 10%. 

A sum of ₹10000 is invested in three schemes of simple interest.
₹4000 were invested in the first scheme.

Amount invested in the second and third scheme = 10000-4000

= ₹6000

Let's assume the amount invested in the second scheme is ₹y.

amount invested in the third scheme = (6000-y)

If the total interest earned after five years is ₹2800.

$$\frac{4000\times\ 4\times\ 5}{100}+\frac{y\times\ 6\times\ 5}{100}+\frac{\left(6000-y\right)\times\ 10\times\ 5}{100}\ =\ 2800$$

$$\frac{4000\times\ 4}{100}+\frac{y\times\ 6}{100}+\frac{\left(6000-y\right)\times\ 10}{100}\ =\ 560$$

$$160+\frac{6y}{100}+\frac{60000-10y}{100}\ =\ 560$$

$$\frac{6y}{100}+\frac{60000-10y}{100}\ =\ 560-160$$

$$\frac{6y}{100}+\frac{60000-10y}{100}\ =\ 400$$

$$6y+60000-10y\ =\ 40000$$

$$6y-10y\ =\ 40000-60000$$

= (6000-5000)

= ₹1000