Question 483140
let one plane speed = x
other plane speed = x+80
combined speed = 2x+80
Distance = 1380
time = 1.5
D=rt
1380=(2x+80)1.5
1380/1.5= 2x+80
920=2x+80
2x=920-80
2x=840
x=420 mph speed of one plane 
other plane 420+80 = 500 mph

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