The sum of the three numbers A, B, and C is 100. It is known that A is 3 times that of B, and C is 5 less than A. How much is C?
甲、乙、丙三个数的和是100，已知甲是乙的3倍，丙比甲少5，丙是多少？
<gadget id="calculator">5 + 100</gadget>
<output>105</output>

<gadget id="calculator">1 + 3 + 3</gadget>
<output>7</output>

<gadget id="calculator">105 / 7</gadget>
<output>15</output>

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">45 - 5</gadget>
<output>40</output>

<result>40</result>