Divide a circle with a perimeter of 15.7 cm into two semicircles, what is the perimeter of each semicircle?
把周长是15.7厘米的圆形平分成两个半圆形，每个半圆形的周长是多少．
<gadget id="calculator">15.7 / 2</gadget>
<output>7.85</output>

<gadget id="calculator">15.7 / 3.14</gadget>
<output>5</output>

<gadget id="calculator">7.85 + 5</gadget>
<output>12.85</output>

<result>12.85</result>