120:30=24:6. If 10 is added to the latter term of the first ratio, what should be the former term of the second ratio to make the ratio valid.
120：30=24：6．若第一个比的后项加10，要使比例成立，则第二个比的前项应该多少．
<gadget id="calculator">30 + 10</gadget>
<output>40</output>

<gadget id="calculator">6 / 40</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">120 * (3/20)</gadget>
<output>18</output>

<gadget id="calculator">24 - 18</gadget>
<output>6</output>

<result>6</result>