When I went to an info session at BU, they said that the writing portion of the test is the grade they most strongly consider. For the other two sections, they just want you over the 50th percentile. (For what it's worth, I scored above the 95th percentile for writing/verbal and around the 50th percentile for quantitative, and got wait listed.) But, I think Emerson ranks those accepted by GPA and verbal/quantitative scores for scholarship awards, so apparently it's more important to them. Practice as much as you can (I barely studied at all, which was a mistake), but I don't think a low math score will totally sink you if you're strong elsewhere!