Question 337220
Starting with:
5 < x - 16 < 12
.
Break it up into a left and right half.
.
Left half:
5 < x - 16
adding 16 to both sides:
21 < x 
.
Right half:
x - 16 < 12
adding 16 to both sides:
x < 28
.
Combining the two we get:
21 < x < 28
Or, in interval notation:
(21, 28)
where:
( or ) signifies do not include number 
whereas
[ or ] signifies include number