Solve for x, y, z
x=\frac{21-7a}{2}
y=a
z=a
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z=y 2x+7y=21 a=z
Reorder the equations.
a=y
Substitute y for z in the equation a=z.
x=\frac{21}{2}-\frac{7}{2}y y=a
Solve the second equation for x and the third equation for y.
x=\frac{21}{2}-\frac{7}{2}a
Substitute a for y in the equation x=\frac{21}{2}-\frac{7}{2}y.
z=a
Substitute a for y in the equation z=y.
x=\frac{21}{2}-\frac{7}{2}a y=a z=a
The system is now solved.
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