Hares and pheasants

After the hunt, hares and pheasants lie in the field. There are a total of 80 heads and 190 feet. How many hares and how many pheasants? (please, without equations)

Correct answer:

z =  15
b =  65

Step-by-step explanation:

$$\begin{gathered} z+b=80 \\ 4z+2b=190 \\ z+b=80 \\ 4\cdot z+2\cdot b=190 \\ b+z=80 \\ 2b+4z=190 \\ Pivot:Row1\leftrightarrow Row2 \\ 2b+4z=190 \\ b+z=80 \\ Row2-\frac{1}{2}\cdot Row1\to Row2 \\ 2b+4z=190 \\ -z=-15 \\ z=\frac{-15}{-1}=15 \\ b=\frac{190-4z}{2}=\frac{190-4\cdot 15}{2}=65 \\ b=65 \\ z=15 \end{gathered}$$

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