A piece of alloy is made of gold and copper and weighs 22 grams. It contains gold and copper in a ratio of 4:7. How many grams of copper does this alloy contain?
一块合金由金和铜铸成，重22克，它含金和铜的比是4：7，这块合金含铜多少克．
<gadget id="calculator">4 + 7</gadget>
<output>11</output>

<gadget id="calculator">7 / 11</gadget>
<output>7/11 = around 0.636364</output>

<gadget id="calculator">22 * (7/11)</gadget>
<output>14</output>

<result>14</result>