Castle tour time

The tour of the castle takes 72 minutes, and the tour of the cellar took half the time compared to the tour of the interiors. In the garden, visitors then spent 20% of the time they were inside (in the cellar and the castle). How long did the tour of the individual parts of the castle take?

Final Answer:

a =  72 min
b =  36 min
c =  21.6 min

Step-by-step explanation:

$a=72=72\text{min}$

$b=a/2=72/2=36\text{min}$

$$\begin{gathered} r=20\%=\frac{20}{100}=\frac{1}{5}=0.2 \\ c=r\cdot (a+b)=0.2\cdot (72+36)=21.6\text{min} \end{gathered}$$

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