In the following question, a matrix of certain characters is given. These characters follow a certain trend, row-wise or column-wise. Find out this trend and choose the missing character accordingly.
7 4 5
8 7 6
3 3 ?
29 19 31

Answer: C. 5

In the first column, 29 - 8 = 7 x 3 = 21.
In the second column, 19 - 7 = 4 x 3 = 12.
Let the missing number in the third column be y.
Then, 31 - 6 = 5 x y  or  5y = 25  or  y = 5.