Решите систему уравнений 30 балов

Решите задачу:

$\left \{ {{x=9+v} \atop {x-2v+1=3}} \right.$

$\left \{ {{x=9+v} \atop {(9+v)-2v=3-1}} \right$

$\left \{ {{x=9+v} \atop {9+v-2v=2}} \right$

$\left \{ {{x=9+v} \atop {9-v=2}} \right$

$\left \{ {{x=9+v} \atop {-v=2-9}} \right$

$\left \{ {{x=9+v} \atop {-v=-7}} \right$

$\left \{ {{x=9+v} \atop {v=7}} \right$

$\left \{ {{x=9+7} \atop {v=7}} \right$

$\left \{ {{x=16} \atop {v=7}} \right$