<=> 18 - 3 + x - 44 + x =55
<=> x + x = 55 - 18 + 3 + 44
<=> 2x = 84
<=> x = 84 : 2
<=> x = 42
Trả lời :.....................................................
18 + ( -3 + x ) - ( 44 - x ) = 55
\(\Leftrightarrow x+x=55-18+3+44\)
\(\Leftrightarrow2x=84\)
\(\Leftrightarrow x=84:2\)
\(\Leftrightarrow x=42\)