Bathtub vent before or after p-trap

I am putting in a new bathtub, the old install had no vent. I am 75" from main 4" stack. Can I use a wye to tie in the new vent to drain line? If so where does it go before or after the p-trap..? Nothing else is on this drain line just the tub.

vent

If it was before the trap, it would not only not protect the trap from loss of seal, but would give sewer gases a direct access into the bathroom. It goes between the trap and the drain line connection.