Ask for a raise or a rate increase

Putting a number in writing to a manager or a long-standing client.

Help me write this so that saying yes is easy and saying no is awkward.

Structure:
1. The ask, with the specific number or percentage, within the first three sentences.
2. Three pieces of evidence: what I took on, what changed because of me, and what it would cost to replace or re-hire. Concrete and dated, no adjectives.
3. An external reference point if I have one: market rate, a competing offer, what I charge others.
4. A clear next step: a conversation by a named date, or a yes or no.

No apology, no "I know budgets are tight", no justification based on my personal costs. Do not ask whether it is possible. State what I am asking for.

Then name the most likely objection and draft two lines answering it.

My situation:
The number:

Declining and negotiating. Saying no cleanly, and putting a number or a counter-offer in writing.