y(n) = x(2n) – x(n-1) is -

i) Static or Dynamic

In y(n) = x(2n) – x(n-1) ,

2n indicates past(for negative n) or future(for positive n) signal;

Also, n-1 indicates signal in past

Hence, the given system is dynamic.

ii) Linear or non-linear

$y_1(n) = x_1(2n) – x_1(n-1) \\ y_2(n) = x_2(2n) – x_2(n-1) \\ \therefore …