Code Language Definitions

First, let's understand the meaning of each symbol used in the code language:

• $A = B$ means 'A is the sister of B'. (A is female)
• $A $ B$ means 'A is the brother of B'. (A is male)
• $A @ B$ means 'A is the wife of B'. (A is female, B is male)
• $A * B$ means 'A is the father of B'. (A is male)

Decoding the Expression: $A $ R = F @ B * K$

Now, let's break down the given expression step by step:

1. $A $ R$: This means 'A is the brother of R'. From this, we know that A is male.
2. $R = F$: This means 'R is the sister of F'. From this, we know that R is female. Since A is the brother of R, and R is the sister of F, it means A and F are siblings, and R is also their sibling. A is male, R is female.
3. $F @ B$: This means 'F is the wife of B'. This tells us F is female (which we already knew) and B is male. B is the husband of F.
4. $B * K$: This means 'B is the father of K'. Since B is the father of K, and F is the wife of B, F must be the mother of K.

Determining A's Relation to K

We have established the following:

• A and F are siblings.
• A is male.
• F is female and is the mother of K.

Since A is the brother of K's mother (F), A is K's maternal uncle.

Therefore, A is related to K as Mother's brother.