A brine is prepared by mixing salt and water in a ratio of 1:40. To prepare 123 grams of brine, how many grams of salt are needed?
一种盐水是由盐和水按1：40的重量配制而成的，要配制123克盐水，需要盐多少克．
<gadget id="calculator">1 * 123</gadget>
<output>123</output>

<gadget id="calculator">1 + 40</gadget>
<output>41</output>

<gadget id="calculator">123 / 41</gadget>
<output>3</output>

<result>3</result>