The number A is (4/15), which is 20% less than the number B, what is the number B?
甲数是(4/15)，比乙数少20%，乙数是多少．
<gadget id="calculator">4 / 15</gadget>
<output>4/15 = around 0.266667</output>

<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">(4/15) / (4/5)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>