What is the equation for this great?

Y = -3x

the line passes through the origin so the y intercept is (0,0)

the line goes down 3 over 1 so the slope is -3x

20000 as first it increases by 2500 then by 5000 so next it will increase by 10000

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.