The number of A is (4/5), 4 times more than the number of B (3/10), what is the number of B?
甲数是(4/5)，比乙数的4倍多(3/10)，乙数是多少？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">(4/5) - (3/10)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(1/2) / 4</gadget>
<output>1/8 = around 0.125</output>

<result>1/8 = around 0.125</result>