Xiaoqian's father used 62.5% of his May salary to buy treasury bonds, and the remaining 12.5% to buy food, leaving 420 yuan in the end. How much is Dad's salary in May?
小倩的爸爸把5月份工资的62.5%买国库券，余下的12.5%买粮，最后剩下420元．爸爸5月份的工资是多少元．
<gadget id="calculator">62.5 / 100</gadget>
<output>0.625</output>

<gadget id="calculator">12.5 / 100</gadget>
<output>0.125</output>

<gadget id="calculator">1 - 0.625 - 0.125</gadget>
<output>0.25</output>

<gadget id="calculator">420 / 0.25</gadget>
<output>1_680</output>

<result>1_680</result>