Xiaohua rode from home to grandma's house. 40% of the whole journey has been done and there are still 2 kilometers away from the midpoint. How many kilometers is it from Xiaohua to grandma's house?
小华骑车从家到外婆家．已经行了全程的40%离中点还有2千米．小华到外婆家有多少千米？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(1/2) - (2/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">2 / (1/10)</gadget>
<output>20</output>

<result>20</result>