-7-x+12= -13+7
\(\Rightarrow\)-x + 5 = -6
\(\Rightarrow\)-x = -11
\(\Rightarrow\) x = 11
\(-7-x+12=-13+7\)
\(\Rightarrow-7-x+12=-6\)
\(\Rightarrow-x=-6+7-12\)
\(\Rightarrow-x=-11\)
\(\Rightarrow x=11\)
Vậy.............
<=>-7-x+12=-13+7
<=>-7-x+12=-6
<=>-7-x =-18
<=> x =11
Vậy x=11