Which variable is most important to the following problem?
dorothy played the first 17 minutes of the hockey game. evelyn then replaced
her for the rest of the half. evelyn started the second half and was replaced by
dorothy with 21 minutes left in the game. if each half is 45 minutes long, how
long did evelyn play during the second half?

a. the length of a half
b. the number of minutes dorothy played in the second half
c. the number of minutes evelyn played in the second half