Answer 
Find out the how many songs john liked.
To prove 
Let us assume that the x be scalar multiple of the like and dislike songs.
As given
John was looking at his streaming music stats. the ratio of songs he liked to disliked was 5:2. 
if he listened to 91 songs total .
Than the equation becomes
5x + 2x = 91
7x = 91

x = 13 
Total number of songs john likes = 5x 
 = 5 × 13 
  = 65 
Therefore the number of songs liked by the john be 65 songs .
Hence proved