A rope is (4/5) of B rope, how much longer is B rope than A rope.
甲绳是乙绳的(4/5)，乙绳比甲绳长多少．
<gadget id="calculator">5 - 4</gadget>
<output>1</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>