Answer:
Option e) 320 s
Explanation:
Here, distance = 3.0 km = 3000 m
The velocity of boat when it is going upstream;
Upstream velocity = velocity of boat in still water - velocity of river flow
So, Upstream velocity 
So,Time to go upstream

The velocity of boat when it is going downstream;
Downstream velocity = velocity of boat in still water + velocity of river flow
So, Downstream velocity 
So,Time to go downstream

So, total time (t) = 
Option E is the correct answer.
Answer:A converging lens is thickest in the middle and causes parallel light rays to converge through the focal point on the opposite side of the lens. A diverging lens is thinner in the middle and causes parallel light rays to diverge away from the focal point on the same side of the lens.
Explanation:
Acceleration=force/mass=28/(10+4)=2m/s^2
force10kg=ma=10*2
force4kg=ma=(10*2)=20
the4 kg is pushing against the 10kg block
vf=vi+at
-10=20*28/14 * t
t=30/2=15sec
i hope this can help you.
PLS HELP ME AS QUICK AS POSSIBLE,
THANKS :)) I'm a bit confused
Can you answer 1 and 2, then confirm 3 :))))