Speed against jetstream = 3255/5 = 651 mph.
Speed with the jetstream = 4055/5 = 811 mph.
Let still air speed of plane be s, and let speed of the jetstream be j.
s - j = 651 .............(1)
s + j = 811 ............(2)
Adding equations (1) and (2), we get:
2s = 1462
s = 731 mph
Plugging the value of s into equation (2) gives:
731 + j = 811
j = 80 mph
The rate of the jet in still air is 731 mph and the rate of the jetstream is 80 mph.
