<PRE><B>Question 1210620</B>
&lt;br&gt;
A general discussion....&lt;br&gt;
If a number x is increased by 13%, then the new number is x plus 13% of x, or&lt;br&gt;
{{{(x)+0.13(x)=1.13(x)}}}&lt;br&gt;
In most problems, percent increases (and percent decreases) are more easily thought of using multiplication instead of addition or subtraction.  So instead of adding 13%, we multiply by 1.13.&lt;br&gt;
This use of multiplication instead of addition or subtraction has HUGE advantages if the problem involves multiple successive percent increases and/or percent decreases.&lt;br&gt;
Similarly, if we know that a number is 1.13 times its previous value, then we know the old number was increased by 13%.&lt;br&gt;
In this problem, we have two consecutive increases of 10%.  That means multiplying the original number by 1.10 (or just 1.1) and then multiplying it by 1.1 again.  So&lt;br&gt;
b = 1.1(a)
c = 1.1(b) = (1.1)(1.1)(a) = 1.21(a)&lt;br&gt;
And from this we see that the overall increase is 21%.&lt;br&gt;
ANSWER: 21%&lt;br&gt;
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