Question

Two airplanes leave Chicago at the same time and fly in opposite directions. If one travels at 450 miles per hour and the other at 550 miles per hour, how long will it take for them to be 4000 miles apart

Answer 1

450t+550t=4,000

1000t=4000

t=4000/1000

t=4 hours they will be 4,000 apart.

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20t+12(4.5-t)=70

20t+54-12t=70

8t=70-54

8t=16

t=16/8

t=2 hours at 20 mph.

proof

20*2+12(4.5-2)=70

40+12(2.5)=70

40+30=70

70=70