Question

The student, as well as his teacher, were going on the field trip.

Answer 1

Answer:

well as his teacher, were going on the field trip.

Explanation:

on the field trip.

Answer 2

Answer:

The student, as well as the teacher, was going on a field trip.

Explanation:

While using "as well as" and with, you are referring to the subject as one. in this sentence, you take the student as the main subject. The teacher is secondary in importance, hence the above answer is correct.