To prepare 120 grams of salt water, the ratio of salt to water is 1:4, how many grams of salt are needed.
要配制盐水120克，已知盐和水的比是1：4，则需要盐多少克．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">120 * (1/5)</gadget>
<output>24</output>

<result>24</result>