Aboat has a mass of 6800 kg. its engines generate a drive force of 4100 n, due west, while the wind exerts a force of 830 n, due east, and the water exerts a resistive force of 1200 n due east. what is the magnitude and direction of the boat's acceleration?

 Let positive be west and negative be east because they are contrasting in directions.

 
The forces are 4100, -830, and -1200

 
The sum of the forces is 4100 – 830 – 1200 = 2070 N. 

Newton’s law F = ma is used. 
2070 = 6800 a 

Isolating a will give us 2070 / 6800 = a

a = 0.34 m/s^2

c) up is the direction the magnetic force is acting on the charge.

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.