Which property does this statement illustrate? 12 + 0 = 12

Two lines that do not intersect are skew. always sometimes or never

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

What is the frequency of the sinusoidal graph?