Temple Magic Puzzle

A person goes to a temple with a "certain amaount" in his pocket, when he gets there, his amount gets doubled. He gives Rs. 16 to a begger from that doubled amount.
Then be goes to a second temple, there remaining of his amount again gets doubled. He again gives Rs. 16 to a begger.
He goes to two more temples, same stuff happens.
After giving Rs. 16 to the begger at the fourth temple, he has no amount left.
So, what was the AMOUNT he had in his pocket when he ARRIVED AT THE FIRST TEMPLE? 

at beginning he has : Rs. x
after he reaches temple, he has: Rs. 2x
after donating in temple 1 : 2x-16 = y (suppose)

similarly,
y
2y
temple 2: 2y-16 = z

z
2z
temple 3: 2z-16 = k

k
2k
temple 4 : 2k-16=0
---------------------
Finally
2(2z-16)-16 = 0
4z-48 = 0 ---------(i)
4(2y-16)-48 = 0
8y-112 = 0
y = 14


x=15

You could simply find the value of z in equation (i) and backtrack.