Solve the Problem $x _ { 1 } = 600 + x _ { 5 }$

Solve the problem.
-The network in the figure shows the traffic flow (in vehicles per hour) over several one-way streets in the downtown area of a certain city during a typical lunch time. Determine the general flow
Pattern for the network.
In other words, find the general solution of the system of equations that describes the flow. In your
General solution let x4 be free.

A) $x _ { 1 } = 600 + x _ { 5 }$
$x _ { 2 } = 400 - x _ { 5 }$
$x _ { 3 } = 300 - x _ { 5 }$
$x _ { 4 } = 300$
$x _ { 5 }$ is free

B) $x 1 = 600 - x _ { 4 }$
$x _ { 2 } = 400 - x _ { 4 }$
$x _ { 3 } = 300 + x _ { 4 }$
$x _ { 4 }$ is free
$x _ { 5 } = 300$

C) $x _ { 1 } = 600 - x _ { 4 }$
$x _ { 2 } = 400 + x _ { 4 }$
$x _ { 3 } = 300 - x _ { 4 }$
$x _ { 4 }$ is free
$x _ { 5 } = 300$

D) $x _ { 1 } = 500 + x _ { 4 }$
$x _ { 2 } = 400 - x _ { 4 }$
$x _ { 3 } = 300 - x _ { 4 }$
$x _ { 4 }$ is free
$x _ { 5 } = 200$