a, b, c are natural numbers, a*b=132, b*c=156, c*a=143, a+b+c=how much.
a，b，c为自然数，a*b=132，b*c=156，c*a=143，a+b+c=多少．
<gadget id="calculator">11 + 12 + 13</gadget>
<output>36</output>

<result>36</result>