Question 1118536
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This problem, although seems to be complicated from the first glance, is actually very simple one unknown problem.


Let x be the amount invested at 5%.


Then you have this "total interest" equation


0.05x + 0.06*(0.25x) + 0.07*(80000 - x - 0.25x) = 4700.


This equations tells everything about itself, you only need to hear it . . . I mean "to read it" . . . 


Please recognize that 0.25x is {{{(1/4)*x}}}.


Your job now is to simplify and solve it for x.
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