To solve this equation, we'll first simplify each side separately:

(2.61 - 4x) / 0.03 + 4.6 = 90
First, we'll simplify the left side by dividing (2.61 - 4x) by 0.03:
(2.61 - 4x) / 0.03 = (87 - 133.33x)
Now we can rewrite the equation:
(87 - 133.33x) + 4.6 = 90
82.4 - 133.33x = 90
-133.33x = 7.6
x = -0.057

Next, let's simplify the right side of the equation:
8.36 - 5.36 / (0.2x + 0.47x) = 7.56
3 / (0.67x) = 7.56
0.67x = 3 / 7.56
0.67x = 0.3968
x = 0.5911

Therefore, the solutions to the equation are x = -0.057 and x = 0.5911.