a, 84 : 4 + 3 mũ 9 : 3 mũ 7 +2021
=84:4+3 mũ 2+2021
=84:4+9+2021
=21+9+2021
=30+2021
= 2051
b 128 - [ 68 + 8 . ( 37 - 35 ) mũ 2 : 4]
=128 - [ 68 + 8 . 2 mũ 2 : 4]
=128 - [ 68 + 8 .4 : 4]
=128 - [ 68 + 32 : 4]
=128 - [ 68 + 8]
=128 - 76
=52
2.tìm x
450 : ( x + 5 ) = 50
x + 5 =450:50
x+5=9
x=9-5
x=4
b, 3 mũ 2018 . ( x - 3 ) = 3 mũ 2022
x - 3= 3 mũ 2022:3^2018
x-3=3 mũ 4
x-3=81
x=81+3
x=84