In a code language, ‘ACID’ is written as ‘XDFE’, and ‘HAND’ is written as ‘EBKE’. How will ‘ZEST’ be written in that language?

To find the code for the word ‘ZEST’, let us first analyze the pattern used in the given examples: ‘ACID’ written as ‘XDFE’ and ‘HAND’ written as ‘EBKE’.

Case 1: ‘ACID’ is written as ‘XDFE’
Let us write the positions of the letters in ‘ACID’ (from the left: A=1, C=3, I=9, D=4) and in ‘XDFE’ (X=24, D=4, F=6, E=5).
Let's examine how each letter changes:
- The first letter ‘A’ is coded to ‘X’. In the reverse alphabetical order, ‘A’ corresponds to ‘Z’. Alternatively, if we subtract 3 from A (with wrapping): A (1) - 3 = X (24).
- The second letter ‘C’ is coded to ‘D’. This is C + 1 = D.
- The third letter ‘I’ is coded to ‘F’. This is I - 3 = F.
- The fourth letter ‘D’ is coded to ‘E’. This is D + 1 = E.
So, the pattern is:
1st letter: -3
2nd letter: +1
3rd letter: -3
4th letter: +1

Case 2: Let us verify this pattern with ‘HAND’ written as ‘EBKE’
- 1st letter: H (8) - 3 = E (5). This matches!
- 2nd letter: A (1) + 1 = B (2). This matches!
- 3rd letter: N (14) - 3 = K (11). This matches!
- 4th letter: D (4) + 1 = E (5). This matches!
The pattern of applying alternate adjustments (-3, +1, -3, +1) is verified.

Applying the pattern to ‘ZEST’:
- 1st letter: Z (26) - 3 = W (23)
- 2nd letter: E (5) + 1 = F (6)
- 3rd letter: S (19) - 3 = P (16)
- 4th letter: T (20) + 1 = U (21)

Putting them together, ‘ZEST’ will be written as WFPU.