The number of A is 80, which is 4 times of the number of B. How much more is the number of A than the number of B?
甲数是80，是乙数的4倍，甲数比乙数多多少．
<gadget id="calculator">80 / 4</gadget>
<output>20</output>

<gadget id="calculator">80 - 20</gadget>
<output>60</output>

<result>60</result>