Answer:
This cannot be simplified any further. That is the simplest you'll get.
X<=-5 is what it looks like to me
plane 1 travels 395 miles in 1 hour
plane 2 travels 422 miles in 1 hour
together, they travel (395+422) 817 miles in 1 hour
to have 2451 miles between then, they'd need to travel

so in 3 hours, they'll be 2451 miles apart
Answer:
30.31%
Step-by-step explanation:
Mark up on selling price is given by markup*100%/selling price
In this case, markup is given as $870 while the selling price is $2870 hence the percentage of narkup to selling price will be given by 
Therefore, the percentage of markup to selling price is approximately 30.31%