A. 50000 + 20000 + 10000 = 8000050000 + (20000 + 10000) = 80000B...

Câu 1.a. 50000 + 20000 + 10000 = 8000050000 + (20000 + 10000) = 80000b. 80000 – 30000 – 20000 = 3000080000 – (30000 + 20000) = 30000