2*7^(2x-9)=7*2^(x-9)

2*14^x/7^9=7^2^x/2^9
14^x*2^10=2^x*7^10
14^x/2^x=7^10/2^10
(14/2)^x=(7/2)^10
7^x=(7/2)^10
x=log(7)(7/2)^10=log(7)7^10 -log(7)2^10=10-10log(7)2=10(1-log(7)2)