## heat of combustion

Calculate the heat of combustion for C2H6 from the following information:
C2H4 + 3 CO2 --> 2 CO2 + 2 H2O /\H f -1409.5 kJ
C2H4 + H2 --> C2H2 /\H f - 136.7 kJ
H2 + 1/2 O2 --> H2O /\H f - 285.5 kJ

i saw someone else ask this question and they were referred to look at Hess's law.. i have done that but i am still unable to solve this i am so stuck.
could someone walk through the steps please?
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 C2H4 + H2 --> C2H2 /\H f - 136.7 kJ C2H4 + 3 CO2 --> 2 CO2 + 2 H2O /\H f -1409.5 kJ these makes no sense(they are not balanced eqs)....did you mean for the product to be C2H6 in the 2nd eq.????????
 no, what i wrote was exactly how its written in the book... is it not able to be solved, possibly they made a typo in the book???