Answer:
13.5
Explanation:

You use PEDMAS - priority of calculation
1) Paranthesis
2) Exponents
3) Divide or Multiple (whichever comes first, reading left to right)
4) Add or Subtract (whichever comes first, reading left to right)
so,
Parenthesis first:

becomes

No exponents, so we skip this step
Left to right for multiply or divide: first comes multiply.

becomes

Now, last one is divide:
