SOLUTION: a person invests 5000 in treasury notes and bonds the notes pay 8% annual interest and the bonds pay 10% annual interest if the annual income is 480 how much is invested in treasur

Let x be invested in treasury notes.

Then (5000-x) is invested in bonds.


Write the total annual interest equation

    0.08x + 0.1*(5000-x) = 480.


Simplify and find x

    0.08x + 500 - 0.1x = 480

    0.08x - 0.1x       = 480 - 500

        -0.02x         =    -20

             x         =    = 1000.


ANSWER.  1000 is invested in treasury notes.


CHECK.   0.08*1000 + 0.1*(5000-1000) = 480, total annual interest.   ! correct !