Solve the equation LaTeX:  \displaystyle \log_{5}(x + 120)-\log_{5}(x + 20)=1 .

Using the quotient property of logarithms gives LaTeX:  \displaystyle \log_{5}\frac{x + 120}{x + 20} = 1 . Making both sides of the equation exponents on the base LaTeX:  \displaystyle 5 gives LaTeX:  \displaystyle \frac{x + 120}{x + 20}=5 . Clearing the fractions by multiplying by the LCD gives LaTeX:  \displaystyle x + 120=5 x + 100 . Isolating LaTeX:  \displaystyle x gives LaTeX:  \displaystyle x = 5 .