There is something VERY wrong with that equation. Check your book.
\(\displaystyle 8(2f - 3) = 4(4f-8)
\)
\(\displaystyle 16f - 24 = 16f - 32
\)
\(\displaystyle 32 - 24 = 16f - 16f\)
\(\displaystyle 8 = 0
\)
The answer I came up w/is -8 but it doesn't fit