Question

If 12 pencils cost $4.00, how much does 20 pencils cost?

Answer 1

`\huge\boxed{\$6(2)/(3)\approx\$6.67}`

Explanation:

`\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=(80)/(12)\\\\x=(20)/(3)\\\\x=6(2)/(3)\Rightarrow x\approx6.67`

`\bold{METHOD\ 2:}\\\\12\ \text{pencils cost}\ \$4.00.\\\\1\ \text{pencil cost}\ \$4.00:12=\$(4)/(12)=\$(1)/(3)\\\\20\ \text{pencils cost}\ \$(1)/(3)*20=\$(20)/(3)=\$6(2)/(3)\approx\$6.67`

Answer 2

$6.66

Explanation:

20 times 4 = 80 and 80 divided by 12 is 6.66666667