Answer:
The value of the given operation is 25.
Explanation:
We where given a rule of operation called
with the form

where a and b are positive integers. Then we where asked to calculate

In order to do it, we have to make two calculations, evaluating this operation properly each time... First we calculate the parentesis as it is the operation of higher hierarchy:

then, we replace that outcome in the second calculation

which is the value asked in the problem.