Lux Investing

Bill gets $126 per year in simple interest from 3 investments. find the amount invested at each value:?

Part is invested at 2%, part is invested at 3%, and part is invested at 4%. There is $500 more invested at 3% than 2%. The amount invested at 4% is three times the amount invested at 3%. Find the amount invested at each value.

Public Comments

1. 0.02a + 0.03b + 0.04c = 126.00 a + 500 = b, therefore, a = b - 500 3b = c sub it all into the first equation 0.02(b - 500) + 0.03b + 0.04(3b) = 126 0.02b - 10 + 0.03b + 0.12b = 126 0.17b - 10 = 126 0.17b = 136 b = 800 $800 is invested at 3% $300 is invested at 2% $2400 is invested at 4%
2. Let amount invested at 2 % = x -----------------------------3 % = y -----------------------------4 % = z 1.02x+1.03y+1.04z=126 -- (1) y=x+500 -- (2) z=3y -- (3) (1) becomes 0.02x+0.03(x+500)+0.04(3x+1500)=126 0.02x+0.03x+0.12x+15+60=126 0.17x+15+60=126 0.17x=126-75 0.17x=51 x=300 interest $6 y=800 ---------$24 z=2400---------$96