Meena S. answered 02/20/17
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Hi Colby,
suppose a man invested $ x which earns 12%
$ y which earns 10%
Amount invested at 8% is twice at 12%,
he invested $ 2x which earns 8% .
Total investment = x+y+2x = 275000
3x +y =275000
y = 275000-3x.......eq 1
Annual income=$ 26000
income from 12% interest for $x= 12x/100
income from 10 % interest for $y =10y/100
income from 8% interest for $2x =16x/100
Total annual income = 26000=12x/100+10y/100+16x/100
2600000=28x+10y........eq 2
substituting value of y from eq 1 to eq 2, we get,
2600000=28x +10(275000-3x)
2600000 = 28x +2750000-30x
2600000 = -2x+2750000
2x= 2750000-2600000
2x= 150000
x= 75000
y = 275000-3(75000) =275000-225000=50000
investment $75000 earns 12%, $50000 earns 10%, $150000 earns 8%.