The answer is 31.
It doesn't matter when or where you learned math, math is a universal. The answer is, always was, and always will be 31. The concept of order of operations has existed in its current form since the 16th century. It is an essential cornerstone of math fundamentals, and exists to help express mathematical hierarchy. Multiplication is above adding and subtracting in the hierarchy, therefore it is always done before them. You do not need brackets or parenthesis, those are used when you want to change the proper order of operations.