a) 1 -  5 + 9 - 13 + 17 -  ... +  201 - 205

Giúp mik với
có lời giải rõ ràng nha

Câu 19. Có ba thùng dầu. Nếu đổ 25% lượng dầu ở thùng A sang thùng B, rồi đổ 1/6 lượng dầu hiện có ở thùng B sang thùng C. Sau đó đổ 20% lượng dầu hiện có ở thùng C sang thùng A thì lúc này số dầu ở ba thùng đều bằng 40 lít. Hỏi lúc đầu thùng B có bao nhiêu lít dầu?

Help me
E.g. Everyone was shocked by his decision. (DECIDE)
He is so ______. He always breaks things and never picks them up. (CARE)
They tried hard but couldn’t find a _________ to the problem. (SOLVE)
We’ve worked together for several months to provide good facilities for ___________ people. (ABLE)
Streets are decorated with _____________ lights and red banners. (COLOR)
The manager criticized the players for showing a lack of ____________. (CONCENTRATE)
Tam’s grandfather was almost ___________ when he saw her painting. (SPEECH)
Mum was angry because the room is messy and _____ (ORGANIZE)
We don’t know how many _________ systems there are in each galaxy. (SUN)
At that time I was young and ___________ , with little experience of the world. (IGNORANCE)
English is an ____________ and important subject. (INTEREST)