how much is invested at each rate?

Question

The co-operative trust fund is P500,000. Part of the fund is invested at an annual interest rate of 6% and the rest is invested at an annual interest rate of 8%. If the income from both investments is P39,000, how much is invested at each rate?

Answer 1

Say, you invested $x$ at $6\%$ so $(1-x)$ is invested at $8\%$. Total amount invested at $6\%$ is then $500,000x$, and at $8\%$ is $500000(1-x)$.

1. Compute the total return for each investment.
2. Add them to get the total return
3. Equate to $39,000$
4. Solve to get $x$