There are three water pipes, the first is (13/15) kilometers long, the second is (4/5) kilometers long, and the third is (2/3) kilometers shorter than the total length of the first and second pipes. How many miles is the third one?
有三条水管，第一条长(13/15)千米，第二条长(4/5)千米，第三条比第一、第二条的总长度短(2/3)千米，第三条长多少千米？
<gadget id="calculator">13 / 15</gadget>
<output>13/15 = around 0.866667</output>

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

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

<gadget id="calculator">(4/5) - (2/3)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">(13/15) + (2/15)</gadget>
<output>1</output>

<result>1</result>