How do I write sets in interval notation

The sets "F" and "H" are defined as follows:

F = { y | y > 4}
H = { y | y <= 8}

Write F n H and F U H using interval notation.
It's possible the set could be empty. If it is, then shoot. I'm dumb.

For a more detailed format, please see:
http://screencast.com/t/w2BWaYzan

Thanks so much in advance!!!

Using interval notation for set F we write:

(4 , +∞)

since y > 4 means any real number greater than 4 all the way to infinity
(notice we do not bracket the 4 here since y > 4 means do not include 4)

Using interval notation for set H we write:

(-∞ , 8]

since y <= 8 means any real number less than or equal to 8 all the way to negative infinity
(notice we bracket the 8 here since y <= 8 means include 8)
(notice also that we never bracket infinity)

Hence

F n H = (4 , +∞) n (-∞ , 8] = (4 , 8 ]
since F intersections H in this zone

F U H = (4 , +∞) U (-∞ , 8] = all real numbers = (-∞ , +∞)
since F and H are combined together (united)