Answer: 10
-----------------------------------------------------------------------------------------
Start at x = 0. When x = 0, y = 0. So (0,0) is on the curve.
Move along the curve going to the right. You'll move up and then come back down to the x axis. If you keep going, you'll go below the x axis and then come back up again. After you reach the x axis a second time, you arrive at x = 10
At this point (reaching x = 10), the curve will repeat the same motion as before. It will go up, come down to the x axis, pass the x axis to go below it, then come back up to the x axis again.
