The number B is (4/15), the number A is 20% less than the number B, what is the number A?
乙数是(4/15)，甲数比乙数少20%，甲数是多少．
<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>16/75 = around 0.213333</output>

<result>16/75 = around 0.213333</result>