Fix Shopify Dynamic Pricing

The product page on my Shopify store already calculates the selling price with a simple algebraic formula, yet the moment an item is added to the cart the platform falls back to the default price and that incorrect amount continues right through to checkout. I need someone who knows Shopify Liquid, AJAX cart scripts, and line-item properties well enough to make the formula-driven price carry flawlessly from product page → cart drawer → checkout.

Scope
• Identify why the maths-formula price is not being passed to the cart or preserved in the checkout payload.
• Adjust the theme code (Liquid, JavaScript / Shopify Scripts or Functions, whichever is most appropriate) so the algebraic equation runs once, stores the result, and surfaces the exact same value in every step of the purchase flow.
• Test across one live theme and a duplicate staging theme to confirm no caching or rounding quirks.

Acceptance
The cart and checkout must always display—and bill—the exact price produced by the algebraic formula shown on the product page, with no manual refreshes or discount codes required on the shopper’s side. Please wrap up with concise, commented code edits and a quick note on any theme files touched so I can maintain future updates with confidence.