The average weight of the two sisters is 43.5kg. If the weight of the mother is added, the average weight of the three is 47.5kg. What is the mother's weight in kg?
姐妹两人平均体重为43.5kg，如果加上母亲的体重，三人平均体重为47.5kg．母亲的体重是多少kg？
<gadget id="calculator">47.5 * 3</gadget>
<output>142.5</output>

<gadget id="calculator">43.5 * 2</gadget>
<output>87</output>

<gadget id="calculator">142.5 - 87</gadget>
<output>55.5</output>

<result>55.5</result>