Solve graphically for the equilibrium flows in a network, including two links connecting one O-D pair. The data for this problem are as follows: Link 1 performance: t_{1} = 1 1/2 * x_{1} ^ 2 Link 2 performance: t_{2} = 3 x_{2} Demand q = 5/u - 1 Flow conservation: q = x1 x2 where t and t are the travel times on link 1 and link 2, respectively, x and x2 are the flows on these links, u is the O-D travel time, and q is the O-D flow. 6.4. Formulate Problem 6.3 as an equivalent minimization. State the first-order con- ditions and solve them for the equilibrium flows