Hey... I think you have some housekeeping issues with the math first...
1) You dropped the -700
2) You lost the "-" sign on the µN2(.156)

LittleMath.jpg

Now... You have 1 equation and 2 unknowns. The only way this can be done is with substitution... You pick the N2 value and you can calculate the N1 value.

Setup a column with N2 values, use the derived formula above, and solve for n1 for each of the N2 values.

Hope I understood what you were trying to do. If not, scan the statics problem and I will check it out.

Signed... Lehigh BSME, '87