Question 1153654
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Let x be the HALF of what Brian invested.


Then you have this equation for the total interest


    0.10*x + 0.14*x = 780  dollars,   or


    0.24x = 780.


Hence,  x = {{{780/0.24}}} = 3250 dollars.


Therefore, the Brian's total investment was twice this amount, or  6500 dollars.
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