\(s_{AB}=s_{BA}=\dfrac{1}{2}s_{tổng}\\ v_{tb}=\dfrac{1}{\dfrac{\dfrac{1}{2}}{40}+\dfrac{\dfrac{1}{2}}{50}}=\dfrac{400}{9}\left(\dfrac{km}{h}\right)\)
https://hoc24.vn/hoi-dap/tim-kiem?id=626908&q=M%E1%BB%99t%20%C3%B4%20t%C3%B4%20chuy%E1%BB%83n%20%C4%91%E1%BB%99ng%20t%E1%BB%AB%20A%20%C4%91%E1%BA%BFn%20B%20v%E1%BB%9Bi%20t%E1%BB%91c%20%C4%91%E1%BB%99%2040km%2Fh%20r%E1%BB%93i%20chuy%E1%BB%83n%20%C4%91%E1%BB%99ng%20ng%C6%B0%E1%BB%A3c%20l%E1%BA%A1i%20t%E1%BB%AB%20B%20v%E1%BB%81%20A%20v%E1%BB%9Bi%20t%E1%BB%91c%20%C4%91%E1%BB%99%2050km%2Fh%20.%20T%C3%ADnh%20t%E1%BB%91c%20%C4%91%E1%BB%99%20trung%20b%C3%ACnh%20c%E1%BA%A3%20%C4%91i%20l%E1%BA%ABn%20v%E1%BB%81%20.%20T%C3%B3m%20t%E1%BA%AFt%20n%E1%BB%AFa%20nha%20%21%21%21