There are two small trees, the first tree is (7/10) meters tall, and the second tree is (2/10) meters shorter. How tall is the second tree?
有两棵小树，第一棵树高(7/10)米，比第二棵矮(2/10)米．第二棵树高多少米？
<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(7/10) + (1/5)</gadget>
<output>9/10 = around 0.9</output>

<result>9/10 = around 0.9</result>