Paper at a landfill decomposes at a constant rate. In 4 weeks, 12 pounds of paper decompose. How much paper decomposes in 12 weeks?

If paper decomposes at a constant rate and in 4 weeks there are 12 pounds of paper decomposed, then:
[tex]\begin{gathered} 4\text{ weeks - 12 pounds} \\ 1\text{ week - x} \\ x=\frac{(1week\rparen\lparen12pounds\rparen}{4\text{ weeks}} \\ x=\text{ 3 pounds/ week. } \\ \\ \end{gathered}[/tex]Each week the paper decomposes 3 pounds. Then:
1 week - 3 pounds
2 weeks- 6 pounds
3 weeks- 9 pounds
4 weeks- 12 pounds
a= 3 pounds, b= 3 pounds, c= 3 pounds, d= 3 pounds
Now:
[tex]\begin{gathered} If\text{ 1 week - 3 pounds} \\ 12\text{ weeks- x} \\ x=\frac{\lparen12weeks\rparen\lparen3pounds\rparen}{1\text{ week}} \\ x=\text{ 36 pounds} \end{gathered}[/tex]Then, after 12 weeks there would be 36 pounds of paper decomposed.