<PRE><B>Question 982656</B>
&lt;br&gt;
A quick informal solution using logical reasoning and some simple mental arithmetic -- if a formal algebraic solution is not required.&lt;br&gt;
Each correct answer earns 5 points; the total points earned for the correct answers is a multiple of 5.&lt;br&gt;
Each incorrect answer loses 2 points; the total points lost for the correct answers is an even number.&lt;br&gt;
Jana&#39;s score was 59, an odd number.  That means the number of correct answers has to be odd, making the total for the correct answers an odd multiple of 5 -- that is, a number with units digit 5.&lt;br&gt;
So 59 has to be some even number less than a number with units digit 5.&lt;br&gt;
The first possibility is 59 = 65-6, which means 13 correct answers an 3 wrong answers.&lt;br&gt;
The next possibility is 59 = 75-16; but that requires far more than 20 questions on the test.&lt;br&gt;
ANSWER: 13 right, 3 wrong; that means 4 questions were unanswered.&lt;br&gt;
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