For simple harmonic motion equation d=9cos(pi/2t) what is the frequency

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.

100 points, hi, i’m not sure how to get the equation from the graph and table.

Solve this equation using substitution. {4x + y = −2} {4x + 6y = 44}