Dad's monthly salary is 8,600 yuan, and mother stipulates that 80% of the monthly salary must be handed over as family expenses. How much pocket money does Dad have each month?
爸爸每月的工资是8600元，妈妈规定每月需上交80%作为家庭开支，则爸爸每月自己有多少零用钱？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">8_600 * (1/5)</gadget>
<output>1_720</output>

<result>1_720</result>