I think the answer is 8 it may be right I hope this helps
When you add up (20N down) and (10N up),
you get a sum of (10N down).
The mass of the object has no effect on the forces.
Now ... I see 5 points for the answer.
Where are the other 25 coming from ?
6mph:
Suppose the boat is traveling on a y axis. The river flow acts on the x axis. Motion on each axes are independent. The linear speed of the boat is not changed. Furthermore the projectile motion is changing, but you're specifically asking about the linear speed of the boat which is unchanged.
Answer:
x = 45 MPH
Explanation:
given,
Average speed of the first half = 75 MPH
Average speed of entire ride = 60 MPH
Average speed of the second half = ?
let the average speed of the second half = x MPH
now,
average of entire ride is given as 60 mph so,


75 + x = 120
x = 120 -75
x = 45 MPH
hence, the average speed of the second half comes out to be 45 MPH.