Any number divided by itself is 1. In the expression-1 times -10 over -1 times -60 ,the -1s in the numerator and the denominator cancel each other out to give the result , or 6.
Let the speed off the walk way be x and speed of the walkway be y x+y=6....i x-y=2....ii adding the above equation we get: 2x=8 thus x=4 ft/s and y=6-4=2 ft/s thus the speed off the walk way is 4 ft/s the speed of the moving walkway is 2 ft/s