In an Analysis of Traffic, a Certain City Estimates the Traffic

Multiple Choice

In an analysis of traffic, a certain city estimates the traffic flow as illustrated in the figure below, where the arrows indicate the flow of traffic. If x1 represents the number of cars traveling from intersection A to intersection B, x2 represents the number of cars traveling from intersection B to intersection C , and so on, we car formulate equations based on the principle that the number of vehicles entering the intersection equals the numt leaving it. Formulate an equation for the traffic at each of the four intersections.

A)
$\begin{array} { l } x _ { 1 } - x _ { 4 } = - 650 \\x _ { 1 } - x _ { 2 } = - 450 \\x _ { 2 } - x _ { 3 } = 1400 \\x _ { 3 } - x _ { 4 } = - 1100\end{array}$
B)
$\begin{array} { l } x _ { 1 } - x _ { 4 } = - 450 \\x _ { 1 } - x _ { 2 } = - 650 \\x _ { 2 } - x _ { 3 } = - 1400 \\x _ { 3 } - x _ { 4 } = 1100\end{array}$
C)
$\begin{array} { l } x _ { 1 } - x _ { 4 } = 450 \\x _ { 1 } - x _ { 2 } = 650 \\x _ { 2 } - x _ { 3 } = 1400 \\x _ { 3 } - x _ { 4 } = - 1100\end{array}$
D)
$\begin{array} { l } x _ { 1 } - x _ { 4 } = 450 \\x _ { 1 } - x _ { 2 } = 650 \\x _ { 2 } - x _ { 3 } = 1400 \\x _ { 3 } - x _ { 4 } = 1100\end{array}$