Two sentences are given below, with three words

Select the combination of letters that when sequentially placed in the blanks of the given letter series will complete the series.

If 42 @ 21 = 18' and 35 @ 27 = 18', then 46 @ 32 = ?'. What will come in place of question mark?

Select the option that is related to the third number in the same way as the second number is related to first number.

24 : 126 :: 48 : ?

Select the option in which the numbers are not related in the same way as are the number of the following set.

(54, 23, 26)  

Select the option that is related to fourth letter-cluster in the same way second letter cluster is related to first letter-cluster.

Select the related number from the given alternatives:

653:87:: 8327: ____

Statement:

Some keyboards are mouse

Only a few dashboards are pianos

All pianos are mouse

Conclusion:

In the following question, select the odd pair from the given alternatives.