We are given:

There seems to be nothing I can do to simplify this equation. However, I can factor out an
since they both have at least an
. Here is what we get:

This is in the simplest form I can get into. I cannot do anything more to simplify this expression. This is your final answer.
The speed of wind and plane are 105 kmph and 15 kmph respectively.
<u>Solution:</u>
Given, it takes 6 hours for a plane to travel 720 km with a tail wind and 8 hours to make the return trip with a head wind.
We have to find the air speed of the plane and speed of the wind.
Now, let the speed wind be "a" and speed of aeroplane be "b"
And, we know that, distance = speed x time.

Now at head wind → 
So, solve (1) and (2) by addition
2a = 210
a = 105
substitute a value in (1) ⇒ 105 + b = 120
⇒ b = 120 – 105 ⇒ b = 15.
Here, relative speed of plane during tail wind is 120 kmph and during head wind is 90 kmph.
Hence, speed of wind and plane are 105 kmph and 15 kmph respectively.
The only option that fits is E, because:
f(10)=4×10+10=50
Hello there, this problem is just basic addition, here is what it would look like

Solve it and we get 78.21