1.  A number when divided successively by 4 and 5 leaves remainders 1 and 4 respectively. When it is successively divided by 5 and 4, then the respective remainders will be:
A. 1, 2
B. 2, 3
C. 3, 2
D. 4, 1

Answer: Option B

Explanation:

 4 | x       y = (5 x 1 + 4) = 9
 --------
 5 | y -1    x  = (4 x y + 1)
             = (4 x 9 + 1) = 37
 --------
   | 1 -4

Now, 37 
when divided successively by 5 and 4, 
we get

 5 | 37
 ---------
 4 | 7 - 2
 ---------
   | 1 - 3
 
Respective remainders are 2 and 3.