A + F → E + D + 3B
A + B → 2C, H = -30 kJ
D + 3B → 2C, H = -80 kJ
E + B → F, H = 120 kJ
What is the overall enthalpy change for the reaction?
a) -10 kJ
b) 10 kJ
c) -50 kJ
d) 50 kJ