In a certain code language, 'SWEDEN' is written as 'TXDEDO', and 'GERMANY' is written as 'HDSNZOZ'. How will 'PORTUGAL' be written in that language?

Let's examine the shift pattern for each letter in SWEDEN → TXDEDO:
Notice that the consonants are increased by +1 and the vowels are decreased by −1:
Scribd

S (consonant) $+1=$ T

W (consonant) $+1=$ X

E (vowel) $-1=$ D

D (consonant) $+1=$ E

E (vowel) $-1=$ D

N (consonant) $+1=$ O

Let's verify with GERMANY → HDSNZOZ:

G (consonant) $+1=$ H

E (vowel) $-1=$ D

R (consonant) $+1=$ S

M (consonant) $+1=$ N

A (vowel) $-1=$ Z

N (consonant) $+1=$ O

Y (consonant) $+1=$ Z
This matches the rule perfectly!

Now, apply this rule (Consonants +1, Vowels −1) to PORTUGAL:

P (consonant) $+1=$ Q

O (vowel) $-1=$ n

R (consonant) $+1=$ S

T (consonant) $+1=$ U

U (vowel) $-1=$ T

G (consonant) $+1=$ H

A (vowel) $-1=$ Z

L (consonant) $+1=$ M

Thus, the code is QNSUTHZM.