<PRE><B>Question 1152425</B>
&lt;br&gt;
Translating the given information directly into equations gives us&lt;br&gt;
{{{2x+y = 55}}}
{{{x+2y = 68}}}&lt;br&gt;
While solving that pair of equations using substitution, as the other tutor did, is valid, there are other ways that are far less work.&lt;br&gt;
The solution with formal algebra using substitution is hard to interpret in everyday language; there are at least a couple of ways to solve the pair of equations using formal algebra for which it is easy to see how common sense makes the solution processes easy to understand.&lt;br&gt;
Here are a couple of solutions that use algebra that is easily described in everyday language.&lt;br&gt;
(1) One standard method for solving pairs of linear equations -- and the most straightforward when the information is given in this way -- is elimination: multiply one or both equations by some constant so that you can use the two resulting equations to eliminate one variable by either adding or subtracting the two equations.&lt;br&gt;
In common sense language, suppose that, instead of buying 1 shirt and 2 pairs of pants for $68, he bought 2 shirts and 4 pairs of pants.  That would cost him $136.  Algebraically, &quot;multiply the second equation by 2&quot;:&lt;br&gt;
{{{x+2y = 68}}} --&gt; {{{2x+4y = 136}}}&lt;br&gt;
Now compare the two purchases (subtract the first equation from this new equation):&lt;br&gt;
{{{2x+4y = 136}}} and {{{2x+y = 55}}} --&gt; {{{3y = 81}}} --&gt; y=27&lt;br&gt;
In everyday language, the difference between the two purchases is now 3 extra pairs of pants, for an extra $81; that means each pair of pants costs $81/3 = $27.&lt;br&gt;
Then use that fact with any of the purchases to determine the cost of each shirt.&lt;br&gt;
(2) And here is a method that uses an unusual algebraic approach but is very understandable with common sense.&lt;br&gt;
Between the two purchases described in the problem, the difference is one more pair of pants and one less shirt, for an increase of $13 in the total cost.  (Algebraically, to find the difference between the two purchases, subtract the first equation from the second):&lt;br&gt;
{{{2x+y = 55}}} and {{{x+2y = 68}}} --&gt; {{{y-x = 13}}}&lt;br&gt;
So let&#39;s make a third purchase where we again add one pair of pants and subtract one shirt.  That gives us three pairs of pants and no shirts, for a cost of $68+$13 = $81.&lt;br&gt;
So again we find the cost of each pair of pants to be $81/3 = $27.</PRE>