TL :
\(12\left(x-81\right):3=4^3+2^3\)
\(12\left(x-81\right):3=64+8\)
\(12\left(x-81\right):3=72\)
\(12\left(x-81\right)=72.3\)
\(12\left(x-81\right)=216\)
\(x-81=216:12\)
\(x-81=18\)
\(\Rightarrow x=109\)
Câu b đang suy nghĩ. ( mik ngu vl )
\(3x-6-x-14=0\)
\(3x-6-1x=0+14\)
\(3x-6-x=14\)
\(\left(3-1\right)x-6=14\)
\(2x=14+6\)
\(2x=20\)
\(\Rightarrow x=10\)