Hanai invested $20,000, part at 3% interest and part 5% interest. The investment returned $800. What is the system of equations that represents this situation

t + f = 20000 3%·t + 5%·f = 800

Step-by-step explanation:

Let t represent the amount invested at three percent; let f represent the amount invested at five percent. The total of these amounts is $20,000. The total of the interest earned by each amount is $800. Of course the interest earned is the amount multiplied by the interest rate.