(1989.1990+3978):(1992.1991-3984)
Cách 1
=(1989.1990+3978):(1992.1991-3984)
=(1989.1990+1989.2):(1992.1991-1992.2)
=[1989.(1990+2)]:[1992.(1991-2)]
=(1989.1992):(1992.1989)
=1
Cách 2
=(3,598,110+3978):(3,996,072-3984)
=3,962,088 : 3,962,088
=1
Cho mk xin hay nhất please
Thank you