Word problem algebra

Question

Twice as many adults as children attended a hockey game. After first period, 530 adults and 25 children left. The number of remaining children became twice as many as the number of adults in arena. How many people were there at hockey game?

Answer 1

a=2c

a-530= (c-25)/2

4c-1060= c-25

3c= 1060-25=1035

c=1035/3= 345 children originally

a= 690 originally

a=160 later

c=320 later