1. Tính
a) 201 + 20 - 112
b) 2190 + 1029 - 9299
c) 999 - 999 + 999 - 999
d) 291 - 912 + 12910
2. Tìm x
a) 29x + 3029 = 3870
b) (x + 3928) - 2019 = 2000000
c) -3x - 201 = -441
d) 291 - 293 + x = 293
e) 283 + 10x = 1283
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1. a) 201+20-112= 221-112= 109
b) 2190+1029-9299= 3219-9299= -5880
c) 999-999+999-999= 0+0=0
d) 291-912+12910= -693+ 12910= 12217
2. a) 29x+3029= 3870
=> 29x= 3870-3029=841
=> x= 841: 29
=> x=29
b) (x+3928)-2019= 2000000
=> x+3928= 2000000+ 2019= 2002019
=> x= 2002019
c) -3x-201=-441
=> -3x= -441+ 201= -240
=> x= 80
d) 291-293+x= 293
=> -2+x= 293
=>x= 293+2=295
e) 283+ 10x= 1283
=> 10x= 1283-283= 1000
=> x=3