As soon as he enters the temple, his money is doubled to 2x. On his way out he donates Rs. 100. Therefore, he is left with Rs. 2x - 100.
2nd Temple:
As soon as he enters the temple, his money is doubled to 2(2x - 100). On his way out he donates another Rs. 100 and he is left out with Rs. (4x - 300).
3rd Temple:
As soon as he enters the temple, his money is doubled to 2(4x - 300). On his way out he donates another Rs. 100 and he is left with Rs. (8x - 700).
4th Temple:
As soon as he enters the temple, his money is doubled to 2(8x - 700). On his way out he donates another Rs. 100 and he is left with Rs. (16x - 1500). According to the question, after his last visit, he completely runs out of money.
Therefore, => 16x - 1500 = 0; => x = 1500/16; => x = 93.75
Rama had started his quest with Rs 93.75 in his pocket.