Use the first law of thermodynamics to answer the following.
a. A gas is heated by supplying it with 250 kJ of thermal energy; at the same time, it is compressed so that 500 kJ of work is done on the gas. Calculate the change in the internal energy of the gas.
b. The same gas is heated as before with 250 kJ of energy. This time the gas is allowed to expand so that it does 200 kJ of work on its surroundings. Calculate the change in the internal energy of the gas.