Question: Fourier series of asymmetric triangle function (1-x)

In the link below to my worksheet I have attempted to construct the Fourier series for the function 1-x.  I should mention that the I often interchnge the variables x & t (probably a bad habit).  It appears that I am getting something close, but my term for n=0 appears to be undefined.  Given the plot I generated the term for n=0 should be approximately 1/4 to get the base of the triangle to intersect the t or x axis.

So I thought if I can get another set of eyes on my work maybe someone can point out what I have incorrect.

Appreciate any assistance

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