There are two buckets of water: one is 8 liters, the other is 13 liters. After adding the same amount of water to the two buckets, the ratio of the water volume in the two buckets is 5:7, so the amount of water added to each bucket is How many liters?
有两桶水：一桶8升，一桶13升，往两个桶中加进同样多的水后，两桶中水量之比是5：7，那麽往每个桶中加进去的水量是多少升？
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">(5/7) * 13</gadget>
<output>65/7 = around 9.285714</output>

<gadget id="calculator">(65/7) - 8</gadget>
<output>9/7 = around 1.285714</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(9/7) / (2/7)</gadget>
<output>9/2 = around 4.5</output>

<result>9/2 = around 4.5</result>