A spaceship traveled 0.5 light-year from Earth to Planet X and 0.1 light-year from Planet X to Planet Y. Then it traveled 0.1 light-year from Planet Y back to Earth . How many light-years did the spaceship travel in all ?
<gadget id="calculator">0.5 + 0.1 + 0.1</gadget>
<output>0.7</output>

<result>0.7</result>