Suppose that f : R → R is a function such that f(x+y) = f(x)+f(y) for all x, y ∈ R. Prove that f has a limit at 0 iff f has a limit at every point c in R.

Aprobability experiment is conducted in which the sample space of the experiment is s={7,8,9,10,11,12,13,14,15,16,17,18}, event f={7,8,9,10,11,12}, and event g={11,12,13,14}. assume that each outcome is equally likely. list the outcomes in f or g. find p(f or g) by counting the number of outcomes in f or g. determine p(f or g) using the general addition rule.