Tractors

Wheel and belt tractors each day plow 8 ha of fields. The wheel tractors would have to work to plow 76 hectares for 12 days. Eight days with the belt tractor together. How many hectares do each day of each tractor?

Correct answer:

a =  3 ha
b =  5 ha

Step-by-step explanation:

$$\begin{gathered} 76=12a+8b \\ 8=a+b \\ 76=12\cdot a+8\cdot b \\ 8=a+b \\ 12a+8b=76 \\ a+b=8 \\ Row2-\frac{1}{12}\cdot Row1\to Row2 \\ 12a+8b=76 \\ 0.33b=1.67 \\ b=\frac{1.66666667}{0.33333333}=5 \\ a=\frac{76-8b}{12}=\frac{76-8\cdot 5}{12}=3=3\text{ha} \\ a=3 \\ b=5 \end{gathered}$$

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