Let x$($t$)$ be a periodic signal with fundamental period T and Fourier series coefficients a k$.$ Derive the Fourier

series coefficients for the following signals in terms of a k$.$

a$.$ x$($t $-$ t $0)+$ x$($t $+$ t $0)$

b$.2$

$2$

c$.$ x$(3$t $-1)$