Both say “it’s their store” it just depends whether you are talking about one or more people. Su is usually he/she but it can mean they/it if you are being non-gender specific. Personally I would go for Es sus tienda but I’m not a native Spanish speaker so I could be wrong
Answer:
1.) I like to drink soda (me gusta beber mierda).
2.)My favorite food is chalupas (mi comida favorita son las chalupas).
3.)My favorite dessert is cheesecake (mi postre favorito es el cheesecake)
Hope this Helps! :)
Explanation: