There are two tanks of goldfish. If 15 goldfish are taken from the first tank and put into the second tank, then the goldfish in the second tank are exactly the ones in the first tank (5/7). It is known that there were originally 35 goldfishes in the second tank. How many more goldfishes were there in the first tank than in the second tank?
有两缸金鱼，如果从第一缸里取出15尾放入第二缸里，这时第二缸里的金鱼正好是第一缸的(5/7)．已知第二缸里原来有金鱼35尾，第一缸里原有的金鱼比第二缸原有的金鱼多多少尾？
<gadget id="calculator">35 + 15</gadget>
<output>50</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">50 / (5/7)</gadget>
<output>70</output>

<gadget id="calculator">70 + 15</gadget>
<output>85</output>

<gadget id="calculator">85 - 35</gadget>
<output>50</output>

<result>50</result>