Lumber consumption calculation

A furniture manufacturing company consumes 124 cubic meters of spruce and oak lumber per month. Spruce lumber consumes three times as many as oak lumber. How much spruce and oak lumber does the company use per month?

Final Answer:

s =  93 m³
d =  31 m³

Step-by-step explanation:

$$\begin{gathered} s+d=124 \\ s=3d \\ s=3\cdot d \\ d+s=124 \\ 3d-s=0 \\ Pivot:Row1\leftrightarrow Row2 \\ Row2-\frac{1}{3}\cdot Row1\to Row2 \\ 1.33s=124 \\ s=\frac{124}{1.33333333}=93 \\ d=\frac{0+s}{3}=\frac{0+93}{3}=31 \\ d=31 \\ s=93=93{\text{m}}^3 \end{gathered}$$

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