Final answer:
The verbs that correctly complete the sentence are 'leads' for the singular subject 'Ted', and 'want' since the clause that follows has a plural subject referring to multiple astronomers at the university.
Step-by-step explanation:
The verbs that correctly complete the sentence are 'leads' and 'want'. The correct sentence is: Ted, with his assistants, leads a team that other astronomers at the university want to join. The subject 'Ted' is singular, and when a singular subject is connected to other nouns using 'with', 'along with', 'together with', 'as well as', or similar expressions, the verb should agree with the first noun which is singular in this case, hence 'leads'. The relative clause 'that other astronomers at the university' is plural, therefore, the verb 'want' is used in its plural form as well.