In a campaign, two teams, A and B, collected some old books. 1/4 of the old books Team A collected was equal to 2/5 of the old books Team B collected. After Team B collected another 987 old books and Team A gave away 2073 old books, the two teams had the same number of old books left. How many old books had each team left in the end?
A==Team A, B==Team B
A - 2073 ==B +987............(2), solve for A, B
Use substitution to get:
A==8,160 books -Team A collected
B==5,100 books -Team B collected
8,160 - 2073 ==6,087 old books that Team A had left
5,100 + 987 == 6,087 old books that Team B had left.