Chapter 5 - Systems of Equations and Inequalities - Concept and Vocabulary Check - Page 537: 2

See below.

We can eliminate $x$ from the first two equations by multiplying the first equation by $-2$ because then $-2x$ and $2x$ "cancel" eachother when adding the equations. We can eliminate $x$ from the first and last equations by multiplying the first equation by $-4$ because then $-4x$ and $4x$ "cancel" eachother when adding the equations.