The number A is the sum of the numbers B, C, and D (1/5), the number B is the sum of the numbers A, C, and D (2/7), and the number C is the number A, B, and D The sum of the numbers (5/13). Given that the number D is 60, find the sum of the numbers A, B, C, and D.
甲数是乙数、丙数、丁数之和的(1/5)，乙数是甲数、丙数、丁数之和的(2/7)，丙数是甲数、乙数，丁数之和的(5/13)．已知丁数是60，求甲、乙、丙、丁四数之和．
<gadget id="calculator">1 + 5</gadget>
<output>6</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">2 + 7</gadget>
<output>9</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">5 + 13</gadget>
<output>18</output>

<gadget id="calculator">5 / 18</gadget>
<output>5/18 = around 0.277778</output>

<gadget id="calculator">1 - (1/6) - (2/9) - (5/18)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">60 / (1/3)</gadget>
<output>180</output>

<result>180</result>