If you divide a number into 3 equal groups and then divide each group in half, you end up with 13. What number did you start with?  Select the correct option:
A) 76
B) 77
C) 78
D) 79
E) None of these
Solution:   Suppose the start number is x Division into 3 equal groups is: x/3, and then in half is (x/3)/2 = 13   x/6 = 13   x = 13 * 6= 
<gadget id="calculator">13 * 6</gadget>
<output>78</output>
78   Answer 78
<result>C</result>
If you divide a number into 3 equal groups and then divide each group in half, you end up with 13. What number did you start with?