Uncle Zhang has 120 black rabbits at home, and the number of black rabbits is 20% less than that of white rabbits. How many white rabbits are there?
张大爷家养黑兔120只，黑兔只数比白兔少20%，养白兔多少只？
<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">120 / (4/5)</gadget>
<output>150</output>

<result>150</result>