Put 15 grams of salt into 35 grams of water. If you want to make the brine contain 20% salt, do you need to add salt or water to the brine? How many grams to add?
把15克盐放入35克水中，如果要使盐水中含盐20%，需要向盐水中加盐还是加水？加多少克？
<gadget id="calculator">15 + 35</gadget>
<output>50</output>

<gadget id="calculator">75 - 50</gadget>
<output>25</output>

<result>25</result>