Jordan and Amari run a 200 m race, and Jordan wins by 21 m. They decide to run the 200 m race again. How far behind the starting line must Jordan start so the second race is a tie?

21m

Step-by-step explanation:

If Jordan won the race by 21 meters, for the race to be a tie Jordan must go back 21 meters.

Since Amari is behind by 21 meters, if Jordan goes back those 21 meters, they'll meet up at the end of the race and tie.