During a certain season, a team won 80 percent of its first

First 100 games -> win 80% = 80
Remaining games -> X
Remaining games won-> (50/100)X
Total games 100first + X -> won 70/100 (100+X)
So..

80+(50/100)x= 70/100 (100+x)
80-70 =(70/100)x-(50/100)x
10 = (20/100)x
x=50 (remaining games) --> Total = 100 +50=150 D