The number of A is 20 less than the number of B (4/5). It is known that the number of A is 40. What is the number of B?
甲数比乙数的(4/5)还少20，已知甲数是40，乙数是多少？
<gadget id="calculator">40 + 20</gadget>
<output>60</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">60 / (4/5)</gadget>
<output>75</output>

<result>75</result>