Two distinct systems have the same amount of stored internal energy. Five hundred joules are added by heat to the first system, and 300 J are added by heat to the second system. What will be the change in internal energy of the first system if it does 200 J of work? How much work will the second system have to do in order to have the same internal energy? O A. 700 J; 0J O B. 300 J; 300 J O C. 700 J; 300 J D. 300 J;0 J

I have got variations in answers when I have asked this question. I have got answers anywhere from 75000 J,  6079.5 J to 74919 J and -6.221kJ.   I need to know the correct answer for this I am hopelessly confused.

27. Assume that the three blocks portrayed in Figure P4.27 move on a frictionless surface and that a 42-N force acts as shown on the 3.0-kg block. Determine (a) the accel- eration given this system, (b) the tension in the cord connecting the 3.0-kg and the 1.0-kg blocks, and (c) the force exerted by the 1.0-kg block on the 2.0-kg block. 42 N 3.0 kg 1.0 kg 2.0 kg

A gasoline engine takes in 1.61 * 10^4 Jof heat and delivers 3700 J of work per cycle. The heat is obtained byburning gasoline with a heat of combustion of 4.60 * 10^4 J/g. What mass of fuel is burned in each cycle?