4^3+5x=0.8*5^3+5x ! решить! надо!

4^(3 + 5x) = 0,8*5^(3 + 5x)
(3 + 5x) ln 4 = ln 0,8 + (3 + 5x) ln 5
(3 + 5x) ln 4 - (3 + 5x) ln 5 = ln 0,8
(3 + 5x) (ln 4 - ln 5) = ln 0,8
(3 + 5x) ln (4/5) = ln (4/5)
3 + 5x = 1
x = -2/5 = -0.4