Verbal Reasoning - Mental Ability Questions

In the following question, which one set of letters when sequentially placed at the gaps in the given letter series shall complete it?
a _ bc _ a _ bcdabc _ da _ cd _

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

Select the related word/letters/number from the given alternatives.
66 : 36 : : 99 : ?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

EFGHI, LMNO, RST, WX, ?

If 3 # 4 % 8 = 6 and 9 % 4 # 3 = 12, then 12 % 6 # 24 = ?

A series is given with one term missing. Choose the correct alternative from the given ones that will complete the series.

2, 3, 7, 16, ?

If 8*2 = 3, 14*18 = -2 and 18*2 = 8, then find the value of 14*10 = ?

In the following question, select the missing number from the given series.

54, 51, 48, 45, 42, ?