<PRE><B>Question 1149394</B>
&lt;br&gt;
Let x be the number of numbers in the original set.&lt;br&gt;
Since the average of the numbers is 23, the sum of the numbers in that set is 23x.&lt;br&gt;
When the number -35 is added to the original set, we end up with a set of (x+1) numbers with an average of 21.&lt;br&gt;
The sum of the numbers in the new set can be written in two different ways:&lt;br&gt;
(1) 23x-35  (the sum of the numbers in the original set, plus the one added number)
(2) 21(x+1)  (the sum of (x+1) numbers with an average of 21)&lt;br&gt;
So&lt;br&gt;
{{{23x-35 = 21(x+1)}}}&lt;br&gt;
Solve using basic algebra....&lt;br&gt;
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