\(2x-2^3.3^2=138\)
\(2x-8.9=138\)
\(2x-72=138\)
\(2x=138+72\)
\(2x=210\)
\(x=210:2\)
\(x=105\)
\(\left(6x-3^4\right).7^3=3.7^4\)
\(\left(6x-3^4\right)=3.7^4:7^3\)
\(\left(6x-3^4\right)=3.7\)
\(6x-81=21\)
\(6x=21+81\)
\(6x=102\)
\(x=102:6\)
\(x=17\)