Answer:
207 mi
Step-by-step explanation:
The two train if they depart at the same time meet at the same time. If  s=v*t then s=vA* tA  and s=vB*tB  so tA=tB  (meeting time tm ),s=sA+sB ; s=vA*tm+vB*tm; s=(vA+vB)*tm so tm =  345mi/(45mi/hr+30mi/hr)= 4,6 hr, now is the distance A since it is how far from Chicago. s_A=v_(A*) t_m=45mi/hr*4,6hr=207mi far from Chicago