There are three numbers A, B, and C. It is known that the sum of A and B is 23.4, the sum of B and C is 48.8, and the sum of A and C is 37.2. What is the sum of the three numbers A, B, and C?
A、B、C三个数，已知A、B两数的和为23.4，B、C两数的和为48.8，A、C两数的和为37.2．A、B、C三个数的和是多少？
<gadget id="calculator">23.4 + 48.8 + 37.2</gadget>
<output>109.4</output>

<gadget id="calculator">109.4 / 2</gadget>
<output>54.7</output>

<result>54.7</result>