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 = ?

Select the missing number from the given responses:

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

In a certain code language, "RUMOUR" is written as "MURRUO". How is "RACKET" written in that code language?

If 18 (9) 3 and 36 (30) 5, then what is the value of A in 19 (A) 18?

In the following question, select the related word pair from the given alternatives.

Power : Watt : : ? : ?

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

In a row of boys, Amit is ranked 12th from top and Ratan is 15th from bottom. They interchange their position. Ratan now becomes 37th from bottom. How many total boys are there in the row?