Book answer is:
My answer is:
I seem to get the same answer for C, but my system of equations is off:
Reverse engineering the solutions shows my system to be incorrect, which seems wierd because I followed a text example step by step.
Why am I wrong?
Wasn't really getting the gist of decomposition until I watched a khan academy video on it, which sort of explained the relatedness of the method. But it was your post that made the lightbulb go on, thank you very much!