In a certain alphabet, 13 letters contain a dot and a straight line. 24 letters contain a straight line but do not contain a dot. If that alphabet has 40 letters, all of which contain either a dot or a straight line or both, how many letters contain a dot but do not contain a straight line?
Choose the correct choice from the following choices
A) 3 B) 8 C) 14 D) 20 E) 28
We are told that all of the letters contain either a dot or a straight line or both, which implies that there are no letters without a dot and a line (no line/no dot box = 0).   First we find the total # of letters with lines:  13 +24= 
<gadget id="calculator"> 13 +24</gadget>
<output>37</output>
37;   Next, we find the total # of letters without line:  40 - 37= 
<gadget id="calculator"> 40 - 37</gadget>
<output>3</output>
3;   Finally, we find the # of letters that contain a dot but do not contain a straight line:  3 - 0= 
<gadget id="calculator">  3 - 0</gadget>
<output>3</output>
3.   3
<result>A</result>
In a certain alphabet, 13 letters contain a dot and a straight line. 24 letters contain a straight line but do not contain a dot. If that alphabet has 40 letters, all of which contain either a dot or a straight line or both, how many letters contain a dot but do not contain a straight line?