Angle of land slope is measured

What will come in place of question mark [?] following the same pattern as given below?

Select the missing number from the given responses.

In each of the following questions, select the related number from the given alternatives:

8/15 : 2/5 : : 16/21 : ?

What will come in the place of question mark?

Study the given pattern carefully and select the number that can replace the question mark (?) in it.  

First row: 4, 6, 18

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

Find the missing term:

Select the related word/letters/number from the given alternatives.

LHX: OEA : : PFT : ?

Select the number from among the given options that can replace the question mark (?) in the following table.

Find the missing number.

20, 30, 42, 56, 72, ?