Answer:
[tex]\huge\boxed{\$6\dfrac{2}{3}\approx\$6.67}[/tex]
Step-by-step explanation:
[tex]\bold{METHOD\ 1:}\\\\\begin{array}{ccc}12&-&\$4.00\\\\20&-&\$x\end{array}\qquad\text{cross multiply}\\\\12x=(20)(4)\\\\12x=80\qquad\text{divide both sides by 12}\\\\x=\dfrac{80}{12}\\\\x=\dfrac{20}{3}\\\\x=6\dfrac{2}{3}\Rightarrow x\approx6.67[/tex]
[tex]\bold{METHOD\ 2:}\\\\12\ \text{pencils cost}\ \$4.00.\\\\1\ \text{pencil cost}\ \$4.00:12=\$\dfrac{4}{12}=\$\dfrac{1}{3}\\\\20\ \text{pencils cost}\ \$\dfrac{1}{3}\times20=\$\dfrac{20}{3}=\$6\dfrac{2}{3}\approx\$6.67[/tex]
