Algebra and logarithms combined

$5x + 2y = -11$

$Now, log_{5}(y-x) - 1 = log_{5}(x+4)$

$or, log_{5}(y-x) - log_{5}5 = log_{5}(x+4)$

$or, log_{5}(\frac{(y-x)}{5}) = log_{5}(x+4)$

Now as the bases are same ( that is equal to 5), that means the logs are equal

$Therefore, (\frac{y-x}{5})= x+4$

$or, y-x = 5(x+4)$

$or, y-x= 5x+20$

$or, y= 6x + 20$

Now you have got two equations , solve them and you will get the values of x and y