The question:
The point of no return for an airplane, flying over water from point A on land to point B on land, is that distance into the trip for which it takes just as much time to go on to B as it does to return to A. The distance from San Francisco to Honolulu is 2387 miles. A plane leaves San Francisco at a speed, in still air, of 400 mi/h. There is a 50mi/h tail wind.
a. Find the point of no return
b. After traveling 1042 miles, the pilot of the plane determines that it is necessary to make an emergency landing. Would it require less time to continue to Honolulu or to return to San Francisco?
My work:
Attempt 1:
a.$\;$ $$450x=350(2387-x)$$
$$450x=825450-350x$$
$$x=1,044.325$$
Point of no return is $1,044.325$ miles away from San Francisco.
b. return to San Francisco
Attempt 2 (failed):
a.$\;$ $$450x=\dfrac{2387-x}{350}$$
$$157500x=2387-x$$ Wait what this doesn't even work -_-
As a general rule, when using algebra, it's best to start by defining what your unknown is supposed to represent. So you might start with:
"Let the distance of the point of no return (PNR) from San Francisco (SF) be $x$ miles".
Then you start by deriving the expressions you wish to equate.
"Ground speed of plane (with tail wind) when travelling in direction from SF to Honolulu (H) = $400 + 50 = 450 \mathrm{mph}$. Ground speed of plane (with tail wind) when travelling in direction from H to SF = $400 - 50 = 350 \mathrm{mph}$".
"Time taken to return from PNR to SF = $\displaystyle \frac{x}{350}$. Time taken to proceed from PNR to H = $\displaystyle \frac{2387-x}{450}$. These times are equal."
"Hence $\displaystyle \frac{x}{350} = \frac{2387-x}{450}$"
After which, you can proceed to cross multiply and get the equation you started with in your first attempt.
Please note that you might well have already been thinking along these lines. But your working gave no sign if you had already "jumped ahead" to the cross multiplication step or if you were simply starting with the wrong equations.
I hope this has been helpful.
The second part can be answered immediately after you get the answer for the first.