Ineed answering this question 5/13t=-9

You divide by 5/13. Remember when dividing fractions you multiply by the reciprocal. 5/13 cancels on the left side, leaving t.

So here you have -9/(5/13), but we can put -9 as -9/1, then instead of dividing by 5/13, multiply by 13/5: 117/5. This evens out, when divided, to t=23.4

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.