Set TAS 360 in the on the
speed scale.
Set heading 215, check
track 210 = 5 degrees port drift.
GS = 64nm in 12 mins = 64/12x60 = 320kts, so find the 320 knot arc below
your 360 TAS and measure out 5 degrees port - mark that spot.
Rotate that spot until it
lines up under your true heading index mark, and read off approx 248M at 50kts.
If they want it true, then just add the easterly mag var = 263T