<h3>
Answer: Choice C</h3>
Work Shown:

So that's why the answer is choice C
The requirement that x is nonzero isn't technically necessary. The original expression simplifies to choice C even when x = 0 is the case. Also, we don't have issues such as division by zero errors that could arise. It's a bit curious why your teacher put in that condition.
The answer would be c 110
C because you need to multiply the adults by 3 to know how many children there are and then you need to exclude the driver which is a-1 meaning taking out 1 adult.
Yes "3x8 = 4x6" does illustrate the commutative property of multiplication.