joffhy
work out how far aircraft a has gone in the 45 mins before the seccond aircraft leaves... this is the distance head start of 131 km
then subtract the speeds so aircraft a is effectively standing still while aircraft b is going 60km/h so then work out how long it takes for b to go 131 at 60km/h that gives u the time taken. then simply use the d=s*t to find how far they go.