It is known that A is the sum of B and C (2/5), and B is the sum of A and C (3/11). The number of A is 15 more than the number of B. Find the sum of the three numbers.
已知甲是乙、丙之和的(2/5)，乙是甲、丙之和的(3/11)，甲数比乙数多15，求三数之和．
<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">11 + 3</gadget>
<output>14</output>

<gadget id="calculator">3 / 14</gadget>
<output>3/14 = around 0.214286</output>

<gadget id="calculator">(2/7) - (3/14)</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">15 / (1/14)</gadget>
<output>210</output>

<result>210</result>