In a triangle, the degree of the first interior angle is three times the degree of the second interior angle; the degree of the third interior angle is half of the degree of the second interior angle, so how many degrees is the first interior angle?
在一个三角形中，第一个内角的度数是第二个内角度数的3倍；第三个内角的度数是第二个内角度数的二分之一，那么第一个内角是多少度．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 + 3 + (1/2)</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">180 / (9/2)</gadget>
<output>40</output>

<gadget id="calculator">40 * 3</gadget>
<output>120</output>

<result>120</result>