There are two fish tanks, A and B, take out 5 goldfish from tank A and put them into tank B. There are the same number of goldfish in both tanks; How many original goldfish.
甲乙两个鱼缸，从甲鱼缸取出5条放入乙鱼缸，两条鱼缸金鱼一样多；如果甲缸取出50%，乙缸取出(1/3)，两缸剩下的金鱼一样多，甲缸原有金鱼多少条．
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">10 * (1/2)</gadget>
<output>5</output>

<gadget id="calculator">10 - 5</gadget>
<output>5</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/2) - (1/3) - 1</gadget>
<output>-5/6 = around -0.833333</output>

<gadget id="calculator">1 + (-5/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">5 / (1/6)</gadget>
<output>30</output>

<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<result>40</result>