Solve Combustion Equation: Get b & c Values

[Jones1987]

Homework Statement

I have worked out the Stoichiometric equation for this Combustion question, however the second part the Air Intake is only 90% which I have also worked out. My question is, during the element balancing how do I obtain values for b and c.

Homework Equations

So this is how it currently stands:

[6.83C + 18H] + 10.20 O2 + 38.34 N2

b CO2 + c CO + d H2O + 38.34 N2

The Attempt at a Solution

I understand this:

C: 6.83 = b + c
H: 18 = 2d
O: 10.20 = 2b + c + d

I have the answer which is;

4.57 CO2 and 2.26 CO

I understand how to obtain the H20 value, but I assumed b + c = 6.83 would just be

b = 3.41
c = 3.41

But this is wrong so could anyone explain how I get the actual values for b and c?

The final answer looks like this:

[Fuel] + 10.20 O2 + 38.35 N2

4.57 CO2 + 2.26 CO + 9 H2O

Help would be much appreciated.

Thanks

 

[jack action]

2 equation, 2 unknowns:

equation #1: c = 6.83 - b

equation #2: c = 10.20 - 2b - d

d is known from 18 = 2d. Equate both equations to find b, then find c.

 

[Jones1987]

Hi, thanks for the reply.

I'm still lost, any chance you (anyone) could walk me through / give the solution to how the end result is obtained?