AP Statistics question. I don’t know how to do #17 at all, please help :’)

The graph shows the distance y, in inches, a pendulum moves to the right (positive displacement) and to the left (negative displacement), for a given number of seconds x. how many seconds are required for the pendulum to move from its resting position and return? enter your answer in the box.

Question 5 spring semester final exam math evaluate

Solve: 3x+y=6 4x-2y=18 show all work !