the numbers after the letters are the exponents

Hi Jaimi,

This looks like a classic case of "combining like terms." Since there is no multiplication or division within the parentheses, you can just remove them. Then, add 3n^{3} + 4n^{3} and subtract 2n^{2} - n^{2}. So, what
do you get? 7n^{3 }+ n^{2}. (The convention is to write the variables with the higher/est exponents first, in an algebraic expression.)