Question 1202412
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Maricopa's Success scholarship fund receives a gift of $105000. 
The money is invested in stocks, bonds, and CDs. 
CDs pay 3.25% interest, bonds pay 5.7% interest, and stocks pay 11.5% interest. 
Maricopa Success invests $35000 more in bonds than in CDs. 
If the annual income from the investments is $7937.50, how much was invested in each account?
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<pre>
Let x be the amount invested in CDs at 3.25%.

Then the amount invested in bonds at 5.7% is (x+35000)  dollars, according to the problem.

The amount invested at 11.5% is the rest  (105000 - x - (x+35000)) = 70000-2x dollars.


Next write the total interest equation

    0.0325x + 0.057(x+35000) + 0.115*(70000-2x) = 7937.50  dollars.


Simplify and find x

    0.0325x + 0.057x - 0.115*(2x) = 7937.50 - 0.057*35000 - 0.115*70000

            -0.1405x             =       -2107.50

                   x             =       {{{(-2107.50)/(-0.1405)}}} =  15000.


<U>ANSWER</U>.  $15000 was invested at CD (at 3.25%);  $15000+$35000 = $50000 was invested in bonds at 5.7%
                and the rest 105000-15000-50000 = 40000 dollars were invested in stocks (at 11.5%).


<U>CHECK</U>.  0.0325*15000 + 0.057*50000 + 0.115*40000 = 7937.50 dollars, total annual interest.  ! correct !
</pre>

Solved, using one single equation in one single unknown.