Rope cutting

Shane has a piece of rope that is 7 4/5 units long. How many pieces does he have if he cuts it into pieces that are each 3/5 of a unit long?

Correct answer:

n =  13

Step-by-step explanation:

$$\begin{gathered} r=7\frac{4}{5}=7+\frac{4}{5}=\frac{7\cdot 5+4}{5}=\frac{35+4}{5}=\frac{39}{5}=7\frac{4}{5}=7.8 \\ u=\frac{3}{5}=0.6 \\ n=r/u=\frac{39}{5}/\frac{3}{5}=\frac{39}{5}:\frac{3}{5}=\frac{39}{5}\cdot \frac{5}{3}=\frac{39\cdot 5}{5\cdot 3}=\frac{195}{15}=13 \end{gathered}$$

Try another example