Four friends ('W', 'X', 'Y', and 'Z') went to dinner and received a bill of Rs. 1,800. They agreed that 'W' would pay half of what the other three paid together. 'X' contributed 10% less than what 'W' paid. 'Y' and 'Z' each paid Rs. 50 more than 'W'. Find the amount paid by 'X'.