## Thinking Mathematically (6th Edition)

1. Let x represent the years spent wathching TV. 2. Let y represent the years spent sleeping. Then, y=x+19 3. The sum of x and y is 37: $x+(x+19)=37$ 4. Solve, answer. $x+(x+19)=37\quad$... simplify LHS $2x+19=37\qquad/-19$ $2x=18\qquad/\div 2$ $x=9$ 9 years of watching TV, 9+19=28 years of sleeping 5. Check: 28 exceeds 9 by 19. Watching TV or sleeping (9+28) equals 37 years (OK). The graph also confirms these results.