Construction 80124

The father offered to work on the construction site for 50 hours as part of a voluntary event. How many hours does he have left after he worked on the construction site for 9 days at 3 and 1 half hours?

Correct answer:

x =  18 ¹⁄₂ = 37/2 h

Step-by-step explanation:

$$\begin{gathered} d=3\frac{1}{2}=3+\frac{1}{2}=\frac{3\cdot 2+1}{2}=\frac{6+1}{2}=\frac{7}{2}=3.5\text{h} \\ o=9\cdot d=9\cdot \frac{7}{2}=\frac{9\cdot 7}{2}=\frac{63}{2}=31.5\text{h} \\ x=50-o=50-\frac{63}{2}=\frac{50\cdot 2}{2}-\frac{63}{2}=\frac{100}{2}-\frac{63}{2}=\frac{100-63}{2}=\frac{37}{2}=\frac{37}{2}\text{h}=18\frac{1}{2}\text{h}=18.5\text{h} \end{gathered}$$

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