log(x-15)-2=-logx
Log(x-15)-2 = -Logx.
Log(x-15) + Logx = 2,
Log((x-15)x) = 2,
Exponential form:
(x-15)x = 10^2,
x^2 - 15x = 100,
x^2 - 15 -100 = 0,
(x+5)(x-20) = 0,
x+5 = 0,
X = -5.
x-20 = 0,
X = 20.
Solution set: X = -5, and X = 20.