

làm giùm mình nha mn . mình thấy khó
từ câu 40 : http://s58.photobucket.com/user/sagacious1/media/20160727_100700_zpsf68y7nrr.jpg.html
http://s58.photobucket.com/user/sagacious1/media/20160727_100710_zpsz7nzq9wt.jpg.html
giải ra luôn nha
từ câu 40 : http://s58.photobucket.com/user/sagacious1/media/20160727_100700_zpsf68y7nrr.jpg.html
http://s58.photobucket.com/user/sagacious1/media/20160727_100710_zpsz7nzq9wt.jpg.html
giải ra luôn nha