Four forces are being applied to move an object to the left. force 1 is pushing to the right at 200 n. force 2 is pushing to the left at 500 n. force 3 is pushing to the right at 100 n. force 4 is pushing to the left at 50 n. what's the net force acting on this object?
a. −250 n
b. 850 n
c. 0 n
d. 250 n

Four forces are being applied to move an object to the left.
Initial Force = 0N

Force 1 is pushing to the right at 200 N.
Force = 200 N

Force 2 is pushing to the left at 500 N.
Force = 200 - 500 = -300 N

Force 3 is pushing to the right at 100 N.
Force = -300 + 100 = -200 N

Force 4 is pushing to the left at 50 N. 
Force = -200 - 50 = -250 N.

So the final answer is -250 N.
The correct answer is letter A. −250 N .

Icant see the pictures 

Most likely a is the answer - because  you generate   38 atp's but also consume an atp.   each atp gives approx. less than 4 kcal so probably a is the closest answer.