Chapter 6 - Algebra: Equations and Inequalities - 6.2 Linear Equations in One Variable and Proportions - Exercise Set 6.2 - Page 362: 57

$-7=x$

$\frac{x-3}{5}-1=\frac{x-5}{4}\\\frac{4x-12}{20}-\frac{20}{20}=\frac{5x-25}{20}\\4x-12-20=5x-25\\-7=x$ Check by plugging it in into the original equation: $\frac{-7-3}{5}-1=-3$. $\frac{-7-5}{4}=-3$. The two sides are equal, thus it is a good solution.