The number A is 100, which is 20% less than the number B, what is the number B, and what is the correct formula
甲数100，比乙数少20%，乙数是多少，正确列式是多少
<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">100 / (4/5)</gadget>
<output>125</output>

<result>125</result>