Depends on the compiler. ; -) I'm pretty sure that I learned multiply, then divide, then add, then subtract in grade school, but by the time college rolled around, the convention had switched to multiply & divide in order from left to right, then add & subtract in order from left to right. So I wouldn't say either answer is right or wrong. People probably just learned different orders of operations. Technically, 9 i s probably the more modern convention. I'll bet the answer people give probably tells you something about their age.

IMO, the best answer is to rewrite the expression in a less-ambiguous way.