Respuesta :

"kilo" means a thousand in Greek, so one kilo-meter is literately a thousand meters.  (some people i know write "k" in slang for a thousand).

so 20 km is 20 thousand meters, which is 20 000 m.
TSO
[tex]\sf 1~kilometer = 1,000 ~meters\\\\20~km= 20 \times 1000~m=\boxed {\sf20,000~m}[/tex]