One Mole of an Ideal Gas at 100 °C, with a Total

One mole of an ideal gas at 100 °C, with a total internal energy of 15,000 J, is mixed with two moles of another ideal gas at 200 °C, with a total internal energy of 30,000 J. What is the total internal energy of the mixture?

A) 15,000 J
B) 22,500 J
C) 25,000 J
D) 45,000 J
E) 67,500 J