| 
 
 
| Question 1048206:  Two planes left the same airport at the same time traveling in opposite directions. The first plane traveled at an average rate of 30 mph slower than the second plane. After 3 hours, the planes were 3150 miles apart.
 Enter an equation that can be used to determine when the planes are 3150 miles apart, where x represents the average rate of the second plane.
 Enter the average rate of change of the slower plane.
 Equation:
 Average rate of change:
 mph
 Answer by Boreal(15235)
      (Show Source): 
You can put this solution on YOUR website! first plane's speed is x-30 mph second plane's speed is x mph
 After 3 hours, they are 3150 miles apart=3*(2x-30 )mph, their combined speed.
 6x-90=3150
 6x=3240
 x=540 mph second plane
 Check
 First  plane's speed is x-30 or  510 mph ANSWER
 Second plane's speed is 540 mph
 Every hour, they are 1050 miles further apart.
 After 3 hours, they are 3150 miles apart.
 | 
  
 | 
 |