In[]:=
Solve[6^x==(6^(40-20)),x]
Out[]=
x
2π

1
Log[6]
+
Log[3656158440062976]
Log[6]
if

1
∈

In[]:=
HoldForm[6^x]/.x->N
2πc1
Log[6]
+
Log[3656158440062976]
Log[6]
/.c1->0//TraditionalForm
Out[]//TraditionalForm=
20.
6
​
In[]:=
Solve[6^x==6^(40-20),x,Reals]
Out[]=
{{x20}}
In[]:=
Print["6^",x/.Solve[6^x==6^(40-20),x,Reals][[1]]]
6^20
In[]:=
IntegerExponent[6^(40-20),6]
Out[]=
20
In[]:=
TraditionalForm[HoldForm[6^x]/.Solve[6^x==6^(40-20),x,Reals][[1]]]
Out[]//TraditionalForm=
20
6
In[]:=
HoldForm[6^x]/.x->IntegerExponent[6^(40-20),6]//TraditionalForm
Out[]//TraditionalForm=
20
6
​