Verbal Reasoning - Mental Ability Questions

In a certain code language, 'x' represents '+', '÷' represents 'x', '-' represents '÷' and '+' represents '-'. Find out the answer to the following question.

18 x 12 ÷ 5 - 10 + 10 = ?

B is the brother of A, and A is the son of C. D is C's father. How is B related to D?

In a certain code language, "NATURE" is written as "TANURE". How is "LISTEN" written in that code language?

From the given alternative words, select the word which cannot be formed using the letters of the given word. SPECULATION

Arrange the given words in the sequence in which they occur in the dictionary.
i. Shortage
ii. Shore
iii. Shamelessly
iv. Shadiness
v. Shallow

In the following question, by using which mathematical operators will the expression become correct?
30 ? 6 ? 4 ? 5 ? 4

Amit and Ritu are a couple. Mrinal and Shonal are brothers. Mrinal is the brother of Ritu. How is shonal related to Amit?

Select the related word/letters/number from the given alternatives. 456 : 15 :: 789 : ?