Peak-hour traffic demand between an origin–destination pair is initially 3500 vehicles. The two routes connecting the pair have performance functions t1 = 2 + 3(x1/c1) and t2 = 4 + 2(x2/c2), where the t’s are travel times in minutes, the x’s are the peak-hour traffic volumes expressed in thousands, and the c’s are the peak-hour route capacities expressed in thousands of vehicles per hour. Initially, the capacities of routes 1 and 2 are 2500 and 4000 veh/h, respectively. A reconstruction project reduces capacity on route 2 to 2000 veh/h. Assuming user equilibrium before and during reconstruction, what reduction in total peak-hour origin–destination traffic flow is needed to ensure that total travel times (summation of all xata’s, where a denotes route) during reconstruction are equal to those before reconstruction?