Among the five numbers A, B, C, D, and E, the average of A, B, and C is 27, the average of C, D, and E is 29, and the sum of these five numbers is 140. The middle number C how many.
在A、B、C、D、E这五个数中，A、B、C的平均数是27，C、D、E的平均数是29，这五个数的和是140，中间数C是多少．
<gadget id="calculator">27 * 3</gadget>
<output>81</output>

<gadget id="calculator">29 * 3</gadget>
<output>87</output>

<gadget id="calculator">87 - 140</gadget>
<output>-53</output>

<gadget id="calculator">81 + (-53)</gadget>
<output>28</output>

<result>28</result>