Find all $x$ such that $1-3x < x + 8 \le 7-x$. Give your answer in interval notation.
Break this into two parts
1 - 3x < x + 8 x + 8 ≤ 7 - x
-7 < 4x 2x ≤ -1
x > -7/4 x ≤ -1/2
( -7/4 , -1/2 ]
+826 
