How to calculate a rental property if is worth

[Esteban Chavez]

I find a Triplex property for a price of $300,000

there are the details of the property.
Great Investment Opportunity! This triplex is the investor's dream! FULLY leased out for a total rental income of $3, 115 (Unit A is $1000 plus (150 utilities), Unit B is $870 plus (100 utilities), Unit C is $995 (utilities included), no HOA, No Flood Area, and low yearly taxes for a more attractive CAP rate!. Each unit features 2 Bedrooms and 1 Bath. All 3 homes have been beautifully updated in 2019 and 2020, NEW Roof installed in 2021, NEW PEX plumbing throughout 2020, NEW electrical throughout 2020. Spacious 9060 sqft lot.

My question here is how can I calculate if this deal is worth it, as a first-time homebuyer, and if is what steps can I take to get into the deal, without the 20% for this deal.