Ryan, as math people, we don't like to write things that are unnecessary. Just like I don't call myself 1 David, but if there are two Davids, we notate as such.
What's my point? There is a 1 in front of the parentheses, though it's -1 because of the minus sign.
5 - 1(3 + 5n) = 5 - 1(3) - 1(5n) = 5 - 3 - 5n = 2 - 5n
Now, usually we put anything with a variable first, so your teacher may want -5n + 2.
Hope this helps!
