Two feeds, 5 mole with 25 J/mole and F with 5 J/mole, product contains two streams, 5 mole with 10 J/mole and 10 mole with 15 J/mole, what is the value of F?

Correct Answer:
5*25 + F*5 = 5*10 + 10*15, => F = 25 mole.