Question 142586
Distance = velocity * time.

total time = 15 hours. 
Distance against wind, 900 miles
Distance with wind, 1200 miles
Ground speed, 150 mph. 

Let the wind speed be w.
Let the time flow against the wind be t. that means the time flown with the wind is {{{15 - t}}}

Construct two equations, as follows.
Against wind
{{{900 = (150 - w) * t}}}
{{{900/(150-w) = t}}}     <--- use this later


With wind:
{{{1200 = (150 + w) * (15-t)}}}
{{{1200 = 2250 + 15w - 150t - wt}}}
{{{-1050 = 15w - 150t - wt}}}

Use the value for t from above.
Substitute that t in the last equation and solve for w. There will be two answers, pck the one that 'makes sense'.