Set this up as a proportion. As proportions you can make the equation:
(5x-8)(5) =(11x-9)(3).
From here, simply distribute and simplify.
(5)(5x) + (5)(-8) = (11x)(3) + (-9)(3)
(25x) + (-40) = (33x) + (-27)
25x - 40 = 33x - 27
Now solve for x.
25x (-25x) -40 = 33x (-25x) -27
-40 = 8x - 27
-40 (+27) = 8x -27 (+27)
-13 = 8x
-13/8 = 8x / 8
-1 5/8 = x
x = -1 5/8