更新1:
sor我打錯左句句子= =" 應該係: If adult's tickets were sold at $7.5 each and student's tickets were sold at $5 each sorrry呀..
更新2:
順便講一講: 可唔可以只係用1個未知數(x,y,z等)黎計呢條數呀.." 我唔想用2個代數黎計,因為我學校都未教..(我宜家f.1昨wor) thx a lot~ 以後有d咩補充我會再講的,所以請答既人兄不時番黎睇