How to add a "___ out of ___" type of question?

There’s no defined question type for this.

What you can do is to create a form question with two fields which you can then move to the question HTML.

Example:

Question HTML:

<div><span class="dest" id="v1"></span> out of <span class="dest" id="v2"></span></div>

Question JS:

Qualtrics.SurveyEngine.addOnReady(function () {
	const quest = this;
	const qc = quest.getQuestionContainer();
	const sources = qc.querySelectorAll(".InputText");
	const destinations = qc.querySelectorAll(".dest");

	destinations.forEach((dest, index) => {
		const src = sources[index];
		dest.insertAdjacentElement("afterbegin", src);
		// To enforce only numbers
		src.type = "number";
	});
});

You can style the text boxes by using the selector .dest .InputText