Question 1147279
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The numbers in the problem make it easy to find a solution by trial and error.<br>
The total amount invested was $2600; the total interest was $72.  That's an interest rate a bit below 3%.<br>
If the two interest rates differ by 2%, they are probably 2% and 4%.  So try those:<br>
$1600 at 2% = $32 interest
$1000 at 4$ = $40 interest<br>
The total interest is $72, as required.<br>
ANSWER: $1600 at 2%; $1000 at 4%.<br>
Now see if you can get that result using algebra.<br>
The interest on $1600 at x percent is {{{1600*(x/100)}}}
The interest on $1000 at (x+2) percent is {{{1000*((x+2)/100)}}}
{{{1600*(x/100)+1000*((x+2)/100) = 72}}}
{{{1600x + 1000(x+2) = 7200}}}<br>
I'll leave it to you to do the little remaining work to verify the answer of 2% and 4%.