To prepare a potion, the mass ratio of powder to water is 2:85. The existing medicine powder is 8 grams, how many grams of water need to be added?
配制一种药水，药粉和水的质量比是2：85．现有药粉8克，需加水多少克？
<gadget id="calculator">8 / 2</gadget>
<output>4</output>

<gadget id="calculator">4 * 85</gadget>
<output>340</output>

<result>340</result>