Question 432608
If two planes start at the same time and fly toward each other, then their respective velocities can be added to each other. Since they are going 420 and 330, respectively, then:
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(420 km/h + 330 km/h)x hrs.=1000km
750 km/h * x hrs.=1000km
x=1000/750 hrs.
""=4/3 hrs
Which equals 1hr. 20min. before they crash into each other.