Chapter 11 - Systems of Equations and Inequalities - 11.7 Systems of Inequalities - 11.7 Assess Your Understanding - Page 783: 5

If a line's equation is $y=mx+b$, then $m$ is its slope. Two lines are parallel if their slopes are equal. Here: $2x+y=4\\x=-2x+4.$ Hence its slope is $-2$. $4x+2y=0\\2x+y=0\\y=-2x.$ Thus its slope is also $-2$. Their slopes are equal, therefore the statement is true.

If a line's equation is $y=mx+b$, then $m$ is its slope. Two lines are parallel if their slopes are equal. Here: $2x+y=4\\x=-2x+4.$ Hence its slope is $-2$. $4x+2y=0\\2x+y=0\\y=-2x.$ Thus its slope is also $-2$. Their slopes are equal, therefore the statement is true.