The compound inequality you are asking for is
3 <= 2x + 5 <= 17.
If you want to get its solution, then
a) subtract 5 from all three components of the inequality
3 - 5 <= 2x <= 17-5, or
-2 <= 2x <= 12
b) divide by 2 all three components of the last inequality
-1 <= x <= 6.
It is your ANSWER. Penelope's number is between -1 and 6, inclusively.