## Introductory Algebra for College Students (7th Edition)

$a.$ Replace x with 4 and y with 1: $2(x+3y)=$ $=2(4+3\cdot 1)$ $=2(4+3)$ $=2(7)$ $=14$ b. If the number 14 is the solution to the equation, then replacing z with 14 should result in a valid equation (the left side should be equal to the right side of the equality sign) $5z-30=40\quad?$ $5(14)-30=40\quad?$ $70-30=40\quad?$ Yes, the equation is valid, 14 is a solution to the equation.