bài 1: tính giá trị biểu thức : 7:0,25-3,2:0,4+8*1,25 là: ..................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... bái 2 :1% của một số bằng 1/2 .số đó là: ......................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................... bài 3:một cửa hàng mua 1kg đương vơi giá 14000 đồng .cửa hàng bán với giá 16 800 đồng .hỏi tiền bán bằng bao nhiêu phần trăm tiền vốn ? ...................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................