25 fg for answer

plane flies 600 miles west into the wind
returns on the same flight path
effect of jet stream on plane is 15 mph
the round trip takes 9 hours
what is speed of plane in still air

must show work

let r be speed of plane in still air (mph)
speed of plane going into wind = r-15
speed of plane going with wind back = r+15
total hours: 600/(r-15)+600/(r+15)=9
multiply both sides by (r-15) and (r+15) we get
1200*r=9*(r+15)*(r-15)
simplifying and expanding you get
0 = r^2-133.33*r - 225
using Pythagorean theorem
r=133.33 (+ or -) sqrt[133.33^2-(4*1*(-225))] \ 2
solving you get r = (133.33+136.67)\2
r=135 mph

how are you using a theory about triangles to solve a quadratic equation?

lol good catch. meant quadratic formula not pythagorean theorem

I concur with 135 mph.