What equity to ask as a cofounder joining a 6 months old startup?

Community, I am in talks with a startup founder about joining them as a co-founder. Please help me either with general guidelines on how to evaluate my equity ask or with advice based on the details I could share below: The 6-month-old startup currently has one founder who is looking for a cofounder as they are unable to manage it all by themselves. While I am unable to share the details of the startup, the startup is a tech-enabled business in the B2C space. Currently, the business is such that we have assisted onboarding of each customer and the team is heavily involved in converting the customer to a paid customer with a decently high ticket size. There is a simple tech product that just works. I will handle technology and marketing, while the founder will take care of direct sales, relationship management, business operations and business financials. The startup currently is making $ 1 for every $ 3 expenditure. All expenses were borne by the founder in the last 6 months. The founder has recently raised money that will keep the company afloat for the next 2 years comfortably. Would love to get guidance on this.