There were 12 male teachers in Dongguan Primary School last semester, 20% less than this semester. How many male teachers are there this semester?
东关小学上学期有男教师12人，比本学期少20%．本学期有男教师多少人？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">12 / (4/5)</gadget>
<output>15</output>

<result>15</result>