Let s = {4, 6, 8} and t = {3, 5, 7}. use the set roster notation to write each of the following sets, and indicate the number of elements that are in each set. (enter your answers as a comma-separated list of ordered pairs.) (a) s ✕ t s ✕ t = number of elements in s ✕ t = (b) t ✕ s t ✕ s = number of elements in t ✕ s = (c) s ✕ s s ✕ s = number of elements in s ✕ s = (d) t ✕ t t ✕ t = number of elements in t ✕ t =