A cup of salt water is 400 grams in total, containing salt (3/10). Pour out (3/4) this cup of brine, how many grams of salt are in the remaining brine?
一杯盐水共400克，含盐(3/10)．把这杯盐水倒出(3/4)，剩下的盐水中含盐多少克？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">400 * (1/4) * (3/10)</gadget>
<output>30</output>

<result>30</result>