Tomás was sure he was going to get an A in his math class. He had studied for every test and done an extra credit assignment. Choose the sentence that is correctly combined:

??!  Neither of the two simple sentences you have written is combined.

Did you instead intend to ask someone to combine the two sentences? If so, then here is one perfectly acceptable combination:

Tomás was sure he was going to get an A in his math class because he had studied for every test and done an extra credit assignment.

Explanation:

i believe that dan is so anxious because he dose not know what awaits him when he gets there. but i dont know to be honest