Students from three classes in grade six donated books to primary schools in mountainous areas. Class 2 donated as many books as Class 1 (8/13), and Class 3 donated fewer books than Class 2 (2/3). Class 1 and Class 3 donated 188 books in total. So how many books were donated by these three classes?
六年级三个班学生给山区的小学捐献图书．二班捐献的书本数是一班的(8/13)，三班捐献的比二班少(2/3)，一班和三班共捐献图书188本．那么这三个班共捐献图书多少本．
<gadget id="calculator">8 / 13</gadget>
<output>8/13 = around 0.615385</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 - (2/3)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(8/13) * (1/3)</gadget>
<output>8/39 = around 0.205128</output>

<gadget id="calculator">1 + (8/39)</gadget>
<output>47/39 = around 1.205128</output>

<gadget id="calculator">188 / (47/39)</gadget>
<output>156</output>

<gadget id="calculator">8 / 39</gadget>
<output>8/39 = around 0.205128</output>

<gadget id="calculator">1 + (8/13) + (8/39)</gadget>
<output>71/39 = around 1.820513</output>

<gadget id="calculator">156 * (71/39)</gadget>
<output>284</output>

<result>284</result>