log5(7+5x)=log5(7-x)+2

log5(7+5x)=log5(7-x)+2

log5(7+5x) - log5(7-x) = 2

log5( (7+5x)/(7-x) ) = 2

5² =  (7+5x)/(7-x)

25(7-x) = (7+5x)

175 - 25х = 7 + 5х

30х = 168

х = 168/30 = 5,6