Although part of your question is missing, you might be referring to the question :
Given that 2x+3y / 3x+4y = 5, find the ratio of y:x
Given : 2x+3y / 3x+4y =5
To find : y : x
Solution :
(2x+3y) / (3x+4y) = 5, or
2x + 3y = 15x + 20y, or
-15x + 2x = 20y - 3y, or
-13x = 17y
Therefore, x/y = -17/13
Hence, y/x = -13/17
y : x = -13 : 17.
The answer is -13 : 17.