Hi,
It depends on what rules you are abiding by...
By the rules of algebra, the correct answer is B) 41.
But if you are going by the pure left to right rules then the answer will be different.
However, in the case where there is a lack of context the rules of algebra would normally be assumed (no previous definitions given).
I've seen calculators that will give the answer as 41 and those that would give the answer as 1. Most modern calculators will give the answer as 41.