Verbal Reasoning - Mental Ability Questions

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

While introducing a boy, Raju says, "He is the son of my wife's sister." How is the boy related to Raju?

In the following question, select the missing number from the given series.
1, 3, 6, 10, 15, ?

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

Power : Watt : : ? : ?

If 40@8 = -5, 30@3 = -10 and 20@5 = -4, then find the value of 60@3 = ?

Select the missing number from the given responses:

If REDUCE= 56, RECYCLE = 71 then REUSE=?

Select the related word/letters/number from the given alternatives. E : V : : D : ?