Answer :
Let Total number of plates = x
And
Total number of puris = y
And from given condition : Leela placed four puris in each plate , then one plate would be left empty.
So,
y = 4 ( x - 1 )
y = 4x - 4 ------------ ( 1 )
And from second condition : Leela places three puris in each plate 1 puri would be left.
So,
y = 3x + 1 ----------- ( 2 )
Now we equate equation 1 and 2 , we get
4x - 4 = 3x + 1
x = 5 , Substitute this value in equation 1 , we get
y = 4 ( 5 ) - 4
y = 20 - 4
y = 16
So,
Total number of plates = 5
And
Total number of puris = 16 ( Ans )