The Freezer temperature is to be kept between 18F and 28F, inclusive
And your question is?
18 </= T </= 28
To determine whether a freezer temperature is within the range of 18°F and 28°F (inclusive), you need to compare the temperature reading to the given range.
If the temperature is equal to or greater than 18°F and equal to or less than 28°F, then it falls within the desired range.
However, if the temperature is below 18°F or above 28°F, then it is outside the desired range and adjustments should be made accordingly.
You can monitor the freezer temperature using a thermometer built into the freezer or by using an external thermometer placed inside the freezer.