bai 1: tinh
a, (3m 6dm + 5dam)x 8=
b, (9km 24m- 71hm 4m) :3=
bai 2 : hay cho biet:
a, the ki XVII tu nam nao den nam nao?
b, nam 1405 thuoc the ki thu may?
c, the ki thu XXI bat dau tu nam nao?
bai 3: dien dau >,<,= thich hop vao o trong
25 tan.......52ta 6 kg 3 phut 20 phut .......... 320 phut
10 ta 4 yen ....... 1040kg 8 phut 10 giay............ 410 giay
8 kg 77 g.......... 87 hg 2/5 the ki ................ 20 nam