Calculation: (3/4)+(4/5)+(5/6)+(6/7)+(9/20)+(13/42)=how much.
计算：(3/4)+(4/5)+(5/6)+(6/7)+(9/20)+(13/42)=多少．
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">6 / 7</gadget>
<output>6/7 = around 0.857143</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">13 / 42</gadget>
<output>13/42 = around 0.309524</output>

<gadget id="calculator">(3/4) + (4/5) + (5/6) + (6/7) + (9/20) + (13/42)</gadget>
<output>4</output>

<result>4</result>