[DutchGirl13]

I have a problem involving a slightly more complex usage of Beer's Law, which has two species instead of one. A_total280nm=0.980. A_total400nm= 0.158. Solution X has a molar absorptivity of 10,090 1/M*cm at 280 nm and 447 1/M*cm at 400 nm. Solution Y has a molar absorptivities of 395 and 9650 1/M*cm at these respective wavelengths. I am asked to find the concentration of these solutions. I set up two equations as shown below:
0.980=10900X+395Y
0.158=447X+9650Y.
I solved the bottom one for Y and got Y=(0.158-447X)/9650= Y, and I plugged it into the top equation and got first 10881.737X+0.006467=0.980 and a concentration of X= 8.96x10^-5M. However, the answer the teacher gave in class was 9.63X10^-5M.  When I solved the top one for Y and substituted the expression into the bottom equation, I got a negative concentration. The only reason that comes to mind for either of these is an algebra error.Would someone please tell me what I did the wrong way?

[Borek]

X= 8.96x10^-5M

That's correct answer for these data.