Double Entry Book Keeping

Hi sir
My F3 exam will be on monday. I need some help
Question:
The profit made by a business in 2007 was $35,400. The proprietor injected new capital of $10,200 during the year and withdrew a monthly salary of $500.
If net assets at the end of 2007 were $95,100, what was the proprietor’s capital at the beginning of the year?
A $50,000
B $55,500
C $63,900
D $134,700

According to my calculation the answer is $50,000 (Option A). But the answer at revision kit is $55,500