Answer:
The canoeing speed is 8mi/h and the stream speed is 2mi/h.
Step-by-step explanation:
Being Vc the speed of canoing and Vs the speed of the stream wmi/e have that

then

using the first equation of the system we have that
Vc = 6mi/h +Vs
replacing
6mi/h+Vs+Vs = 10mi/h
2Vs = 4mi/h
Vs = 2mi/h
then going back
Vc = 6mi/h + 2mi/h = 8 mi/h