Question 360260
let p = speed of the wind in still air, w = speed of the wind.

Then {{{matrix(2,1, 3(p+w) = 648,6(p-w) = 648)}}}.
{{{matrix(2,1, p+w = 216,p-w = 108)}}} after dividing by 3 and 6, respectively,
Adding corresponding sides of the equations, we get
2p = 324,
p = 162, and w = 216-162 = 54.
The plane goes 162 mph, the wind 54 mph.