a) 39 + ( 31 - x ) = 70
31 - x = 39 + 70
31 - x = 109
=> x = 31 - 109
=> x = -78
39 + ( 31 - x ) = 70
31 - x = 70 - 39
31 - x = 31
x = 31 - 31
x = 0
39 + ( 31 - x ) = 70
31 - x = 70 - 39
31 - x = 31
x = 31 - 31
x = 0
nhâm ) 39 + ( 31 - x ) = 70
31 - x = 70 - 39
31 - x = 31
=> x = 0
39 + ( 31 - x ) = 70
31 - x = 70 - 39
31 - x = 31
x = 31 - 31
x = 0 .
k tui .
39+(31-x)=70
<=>31-x=70-39
<=>31-x=31
<=>x=31-31
<=>x=0
Vậy x=...
k mik nha
39 + ( 31 - x ) = 70
31 - x = 70 - 39
31 - x = 31
x = 31 - 31
x=0