glass of 450mL fresh milk contains about (3/10)g of calcium, which accounts for (3/8) of the calcium needed by an adult for a day. How many grams of calcium does an adult need per day?
一杯450mL的鲜牛奶大约含有(3/10)g的钙质，占一个成年人一天所需钙质的(3/8)．一个成年人一天大约需要多少g钙质．
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">(3/10) / (3/8)</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>