A certain car first traveled 50 kilometers eastward, and then 30 kilometers westward. At this time, how many kilometers away is the car from the starting point?
某汽车先向东前进了50千米，后向西前进了30千米此时汽车在离出发地多少千米．
<gadget id="calculator">50 + (-30)</gadget>
<output>20</output>

<result>20</result>