Housekeeper 7695

At six o'clock, the housekeeper will start cutting his bow, which will take 12 hours. Two sons come to help him in an hour, and they will be together in 3 hours. How much would it take for just two sons to mow the bow?

Correct answer:

s =  4.5 h

Step-by-step explanation:

$$\begin{gathered} 4/12+3/s=1 \\ 4/12s+3=s \\ 4/12\cdot s+3=s \\ 8s=36 \\ s=\frac{36}{8}=4.5 \\ s=\frac{9}{2}=4.5=4.5\text{h} \end{gathered}$$

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