Given:
When flying against a headwind:
Distance = 450 miles
Speed = v - 35 mph
When flying tailwind:
Distance = 702 miles
Speed = v + 35 mph
Let's find the speed of the helicopter.
Apply the formula:

Where:
v is the speed
d is the distance
t is the time
Rewrite the equation for time (t):

Thus, we have the equations:
Time when flying against headwind:

Time when flying tailwind:

Eliminate the equal sides of the equations and combine.
We have:

Let's solve for the speed, v.
Cross multiply:

Apply distributive property:

subtract 15750 from both sides:

Subtract 702v from both sides:

Divide both sides by -252:

Therefore, the speed of the helicopter is 160 mph
ANSWER:
s = 160 mph