(0.75)^2x-3=(1. 1/3)^5-x

не совсем правильно

0,75^(2x-3)=(1. 1/3)^(5-x)
(3/4)^(2x-3)=(4/3)^(5-x)
(3/4)^(2x-3)=((3/4)⁻¹)^(5-x)
(3/4)^(2x-3)=(3/4)^(x-5)
2x-3=x-5

x=-2