In the ratio 4:8=5:10, if 4 is added to the preceding term of the first ratio, how much should be added to the preceding term of the second ratio to make this ratio still valid?
在比例4：8=5：10中，如果第一个比的前项加上4，要使这个比例仍然成立，第二个比的前项加上多少
<gadget id="calculator">4 + 4</gadget>
<output>8</output>

<gadget id="calculator">10 / 8</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">8 * (5/4)</gadget>
<output>10</output>

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

<result>5</result>