The correct answer is to find whoever wrote the problem in that way, and slap them silly.

There are two possible interpretations. Either one could be written unambiguously. Writing it in this way is just bad notation.

I got the impression that whoever posted this originally created it as a sort of puzzle or mathematics test, or to illustrate varying precedence over time. I doubt if anybody is still alive from the time when BODMAS/PEMDAS wasn't universal so for practical modern purposes the equation is not ambiguous. In fact it isn't possible to write an ambiguous (valid) equation.

In UK schools we are taught BODMAS: Brackets Of (as in "to the power of") Divide and Multiply Add and Subtract

In the US they say PEMDAS (P and E being parentheses and exponent respectively). No doubt other countries use something equivalent.

If you apply this rule you will get the right answer, as long as you also remember to carry out operations with the same precedence left-to-right.