Question 1048206
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.