White chalk is 28 boxes less than red chalk, and white chalk is 80% of red chalk. How many boxes of red chalk are there?
白粉笔比红粉笔少28盒，其中白粉笔是红粉笔的80%，红粉笔有多少盒？
<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">28 / (1/5)</gadget>
<output>140</output>

<result>140</result>