## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

Evaluate $\frac{x-y}{3}$ when x is twice y and x is 12. Write an expression for y in terms of x. $2y=x\longrightarrow$ Divide both sides by 2. $2y\div2=x\div2\longrightarrow$ Simplify. $y=\frac{x}{2}$ Substitute for y in the original formula. $\frac{x-y}{3}=\longrightarrow$ Substitute for y in the original formula. $\frac{x-\frac{x}{2}}{3}=\longrightarrow$ Substitute 12 for x. $\frac{12-\frac{12}{2}}{3}=\longrightarrow$ Solve $\frac{12-6}{3}=$ $\frac{6}{3}=$ $2$