Question 250290
D=RT
210=R*10
210=10R
R=210/10
ER-21 MPH. FOR THE TRIP DOWNSTREAM.
210=R*70
R=210/70
R=3 MPH FOR THE TRIP UPSTREAM.
(10-3)/2=7/2=3.5 MPH IS THE CURRENT SPEED.
10-3.5=6.5 MPH FOR THE BOAT.
3+3.5=6.5 DITTO.