Answer:
Points required to win the trophy =500 
 Points Kristen already scored = 418 
 Let Kristen require x points to win the trophy. 
 So making an equation using the information we have,
418+x=500 
 Now we have to solve this equation to get the value of x . 
 subtracting 418 from 500 , we have,
x=500-418 
x=82 
 So Kristen require at least 82 points to win the trophy.