There used to be (13/20) square meters of green grassland in Little Angel Forest Park. After pulling out (1/2) square meters, (7/10) square meters of grassland was planted again. Little Angel Forest Park now has green grassland What is the area in square meters?
小天使森林公园原来有(13/20)平方米的青草地，拔掉了(1/2)平方米后，又种了(7/10)平方米的草地，小天使森林公园现在有青草地的面积是多少平方米？
<gadget id="calculator">13 / 20</gadget>
<output>13/20 = around 0.65</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(13/20) - (1/2)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">(3/20) + (7/10)</gadget>
<output>17/20 = around 0.85</output>

<result>17/20 = around 0.85</result>