The four share the dining expenses of 180 yuan. The first person pays half of what the others pay, the second person pays (1/3) of the total amount paid by the others, and the third person pays (1/4) the total amount paid by the others , how much did the fourth person pay?
四人共同分担180元的就餐款．第一个人付的钱是其他人的一半，第二个人付的钱是其他人付钱总数的(1/3)，第三个人付的钱是其他人付钱总数的(1/4)，第四个人付了多少元？
<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 + 3</gadget>
<output>4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/3) - (1/4) - (1/5)</gadget>
<output>13/60 = around 0.216667</output>

<gadget id="calculator">180 * (13/60)</gadget>
<output>39</output>

<result>39</result>