In the ratio 3:5=9:15, if you add 10 to the last term of the first ratio, how much should be added to the last term of the second ratio, so that the ratio can be established.
在比例3：5=9：15中，如果将第一个比的后项加10，第二个比的后项应加上多少，比例才能成立．
<gadget id="calculator">5 + 10</gadget>
<output>15</output>

<gadget id="calculator">9 / 3</gadget>
<output>3</output>

<gadget id="calculator">15 * 3</gadget>
<output>45</output>

<gadget id="calculator">45 - 15</gadget>
<output>30</output>

<result>30</result>