<PRE><B>Question 1146729</B>
&lt;br&gt;
(1) A setup for a traditional algebraic solution....&lt;br&gt;
x amount at 6%, plus ($9000-x) at 11%, yields $600 interest:&lt;br&gt;
{{{.06(x)+.11(9000-x) = 600}}}&lt;br&gt;
Solving involves only basic algebra; but the decimals make the calculations a bit ugly.  I leave it to you to finish the solution by that path.&lt;br&gt;
Here is a faster way to the answer for a &quot;mixture&quot; problem like this.&lt;br&gt;
$9000 all at 6% --&gt; $540 interest
$9000 mixed --&gt; $600 interest
$9000 all at 11% --&gt; $990 interest&lt;br&gt;
Look where the actual interest of $600 lies between $540 and $990:&lt;br&gt;
540 to 990 = 450; 540 to 600 = 60; 60/450 = 2/15.&lt;br&gt;
$600 is 2/15 of the way from $540 to $990; that means 2/15 of the total is invested at the higher rate.&lt;br&gt;
ANSWER: 2/15 of the $9000, or $1200, at 11%; the other $7800 at 6%.&lt;br&gt;
CHECK: .06(7800)+.11(1200) = 468+132 = 600</PRE>