Madams

During spring cleaning, ladies were going to wash the windows. Mother takes 2 hours to wash all the windows, the grandmother takes 2 times longer, and Paula washes all the windows in 2 hours. How many hours will you spend washing the windows of this "women's team" if working together?

Final Answer:

x =  0.8 h

Step-by-step explanation:

$$\begin{gathered} t_1=2\text{h} \\ {t}_2=t_1\cdot 2=2\cdot 2=4\text{h} \\ {t}_3=2\text{h} \\ h=\frac{1}{t_1}+\frac{1}{t_2}+\frac{1}{t_3}=\frac{1}{2}+\frac{1}{4}+\frac{1}{2}=\frac{2}{4}+\frac{1}{4}+\frac{2}{4}=\frac{2+1+2}{4}=\frac{5}{4}=1.25 \\ x\cdot h=1 \\ x=1/h=1/\frac{5}{4}=1:\frac{5}{4}=1\cdot \frac{4}{5}=\frac{1\cdot 4}{5}=\frac{4}{5}=\frac{4}{5}\text{h}=0.8\text{h} \end{gathered}$$

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