a) x - 920 = 99920
x = 99920 + 920
x = 100840
b) x + 90 - (-29) = 10020
x + 90 = 10020 + (-21)
x + 90 = 9991
x = 9991 - 90
x = 9901
c) 99 - x = 90
x = 99 - 90
x = 9
d) -x + 93 = -1
-x = -1 - 93
-x = -94
a, x - 920 = 99920 c, 99 - x = 90
x = 99920 + 920 x = 99 - 90
x = 100840 x = 9
Vậy x = 100840 Vậy x = 9
b,x + 90 - (-29) = 100020
x + 90 = 100020 + ( -29 )
x + 90 = 99991
x = 99991 - 90
x = 99901
Vậy x = 99901