Question 78636
540x+660(x-1)=1800
540x+660x-660=1800
1200x=1800+660
1200x=2460
x=2460/1200
x=2.05 hours after the first place left Chicago the two planes will meet.
proof
540*2.05+660(2.05-1)=1800
1107+660(1.05)=1800
1107+693=1800
1800=1800