Ten packages

Tina has ten packages of yarn to knit a scarf.
She uses 1/3 of a package of yarn for each inch of length she adds to the scarf.
If Tina uses all the yarn, how long will her scarf be?

Correct answer:

x =  30 in

Step-by-step explanation:

$$\begin{gathered} n=10 \\ h=1/\frac{1}{3}=1:\frac{1}{3}=1\cdot \frac{3}{1}=\frac{1\cdot 3}{1}=\frac{3}{1}=3\text{in/y} \\ x=n\cdot h=10\cdot 3=30\text{in} \end{gathered}$$

Try another example