The perimeter of a triangle is (7/10) decimeters, and the length of two sides is (1/5) decimeters. What is the length of the other side? What kind of triangle is this?
一个三角形的周长是(7/10)分米，其中有两条边的长度都是(1/5)分米，还有一条边的长度是多少分米？这是一个什么样的三角形？
<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

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

<gadget id="calculator">(1/5) * 2</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(7/10) - (2/5)</gadget>
<output>3/10 = around 0.3</output>

<result>3/10 = around 0.3</result>