SOLUTION: Two planes leave at the same time and head in opposite directions. One travels 80mph faster than the other. After 3 hours, they are 2,940 miles apart. What is the rate of each p

Algebra ->  Expressions-with-variables -> SOLUTION: Two planes leave at the same time and head in opposite directions. One travels 80mph faster than the other. After 3 hours, they are 2,940 miles apart. What is the rate of each p      Log On


   

Question 30699: Two planes leave at the same time and head in opposite directions. One travels 80mph faster than the other. After 3 hours, they are 2,940 miles apart. What is the rate of each plane? Plane DISABLED_event_one= b + 80 and plane two = b. The rest of this is not calculating for me. I know that the three hours figure in there somehow yet can't figure where. Please help me. Thanks
Found 2 solutions by Paul, checkley71:
Answer by Paul(988) About Me  (Show Source):
You can put this solution on YOUR website!
Speed of first palne = x
Speed of second plane = x+80
Equation:
3(x+x+80)=2940
6x+240=2940
6x=2700
x=450

450+80=530
Hence, the speed of one plane is 430mph and speed of another is 530mph.
Paul.

Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
3X+3(X+80)=2940 3 HOURS FOR PLANE 1 AT SPEED X AND 3 HOURS FOR PLANE 2 AT (X+80) EQUALS THE TOTAL DISTANCE APART OF 2940
3X+3X+240=2940 OR 6X=2940-240 OR 6X=2700 OR X=2700/6 OR X=450MPH FOR PLANE 1 &
450+80 OR 530MPH FOR PLANE 2.