An aircraft travels 1000. km west and then travels 500. km west what is its total displacement?

If im correct you just add them together? so it might just be 1500 km west cause they are traveling in the same direction. i could be wrong but hope this helps.

this allows people to make the best decision or pursue the best option. when alternatives are weighed using their advantages and disadvantages, the option whose disadvantages outweigh the advantages (based on a qualitative or quantitative analysis) are shunned while those whose advantages outweigh their disadvantages are pursued.  

reserve is the answer