Select the set in which the numbers are related in the same way as are the numbers of the following sets. (NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E. g. 13 – Operations on 13 such as adding / subtracting / multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

(12, 42, 7)

(13, 52, 8)

Find the missing number?
2, 15, 41, 80, ?

What will come at the place ___ ?In the given series? 
 BZA, DYC, FXE, ?, JVI

Study the given information carefully and answer the given questions.
Auditions for a show were held in seven different cities of India- Chennai, Bengaluru, Cochin, Mumbai, Delhi, Bhopal and Kolkata, not necessarily in the same order, during the first seven months of the year 2011 (starting on January and ending in July). The auditions were held only in one city during a month. Auditions in only four cities were held between the Kolkata audition and the Cochin audition. The Kolkata Audition was not held in June. Only one audition was held between the Kolkata audition and the Bengaluru audition The Chennai audition was held immediately after the Kolkata audition. The Delhi audition was held immediately before the Bhopal audition. The Bhopal audition was not held in May.
Which of the following statements is true according to the given sequence?

6 : 12 : : 20 : ?

Six trucks K, M, O, Q, S and U are parked around a circular path facing the center, Q is second to the left of U. S is to the immediate left of M. K is second to the right of O. O is to the immediate right of Q. Which truck is parked second to the left of O?

Some question is solved on the basis of certain system. On the same basis find out the correct answer from amongst.
a =12 (390) 8,  b=7(134) 5, c=5(?) 12

If ‘+’ means ‘÷’, `-` means `×`, `÷` means `+` and `×` means `-`, then
36 × 12 + 4 ÷ 6 + 2 - 3 = ?