Use a tape diagram. Draw your diagram on paper, take a picture, and upload it using the image upload icon If you do not have the ability to upload an image of your work type "Diagram is on paper."

Period is the time it takes for one “cycle” to complete. in the parent sine function, period is 2*pi since sin(0) = 0, sin(pi/2) = 1, sin(pi) = 0, sin(3pi/2) = -1, and sin(2pi) = 0. at that point, the sequence repeats itself. i’m not sure if your graph is similar to the sine function since you didn’t provide a picture, but you can find the period by looking at a graph.

21/3 is the answer i believe