There is brine with 25% salt in a container. If 20 grams of water are added, the salt content of the brine will be 15%. How many grams of the original brine is in this container?
一个容器内有含盐25%的盐水，若再加20克水，盐水的含盐率为15%，这个容器内原有盐水有多少克？
<gadget id="calculator">0.25 - 0.15</gadget>
<output>0.1</output>

<gadget id="calculator">3 / 0.1</gadget>
<output>30</output>

<result>30</result>