Can someone help me on this Math problem please?

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<p>If you try googling “a club is buying boxes” you will find many discussions of this problem, including here:</p>

<p><a href=“Math question - SAT Preparation - College Confidential Forums”>http://talk.collegeconfidential.com/sat-preparation/1185394-math-question.html&lt;/a&gt;&lt;/p&gt;

<p>If this type of problem bothers you, you may want to try an SAT classic trick: make up numbers for the variables x and c, get a numeric answer to the question and then put your x and c values into each answer. Rule out any answer that doesn’t match the numeric answer you got.</p>