Clean 400 Page SAT Math PDF

I have a 400-page PDF packed with SAT Math questions that currently displays the same watermark in the identical spot on every single page. Converting to Word wrecked the formatting, so I need a direct, professional watermark removal that keeps everything else—equations, symbols, tables, graphs, margins and pagination—pixel-perfect.

What must stay unchanged
• Original page size, resolution and compression settings
• All mathematical notation, vector lines and embedded fonts
• Existing hyperlinks, bookmarks and table of contents (if any)

Final deliverable
• One watermark-free PDF that visually matches the source file in every respect except the missing mark

Please tell me how long this will take you and the total cost for the full 400 pages when you place your bid. A short sample of your process on one page is welcome but not mandatory.