How many simple fractions are there that have a fraction value greater than (1/2) and less than 4, with a denominator of 13?
分数值比(1/2)大，比4小，分母是13的最简分数有多少个．
<gadget id="calculator">52 - 7 - 3</gadget>
<output>42</output>

<result>42</result>