Answer :

5x = 2x + 9, where 5x > 0 and 2x + 9 > 0 ;
Then, 3x = 9 ;
Then, x = 3 ;
Verify : 5 × 3 = 2 × 3 + 9 ;correct !
            5 × 3 > 0 ; correct !
            2 × 3 + 9 > 0; correct !