Answer:
trabaja
Step-by-step explanation:
conjugations are simple if you know them. for trabajar you take the ending (-ar) and replace it with some other letters that make it grammatically correct. since trabajar is in the infinitive form at the moment you need to conjugate it (the ending) for it to make sense. so for the (-ar) endings, it would go like this
yo( i ) - o
tú ( you ) - as
él/ella/usted ( he/she/usted(formal)) - a
nosotros/nosotras (we(masc or fem)) - amos
ellos/ellas/ustedes (they (masc. fem. or formal) - an.
since we are talking about USTED we use the él/ella/usted form meaning replacing the -ar ending with an -a ending. hope this helps let me know if you have any questions:)