Respuesta :

Starting from the first term...
14, -14, -7, 0, 7, 14, -14, -7, 0, 7, 14, -14, -7, 0, 7, 14, -14, -7, 0
Zero is the 19th term.

I hope you are satisfied with my answer.
a19=a1+18d
a19=-14+126=112