To solve this problem you must apply the proccedure shown below:
 1- The formula for calculate the area of this rectangle is:
 

 Where 
 is the length and 
 is the heigth.
 2. Let's call identify the heigth with the variable 
.
 3. If the length is 
 longer than the heigth, you have:
 

 4. Therefore, you can write the following polynomial expression:
 

 5. If you know the value of the heigth, you can susbstitute it into the polynomial expression shown above and you will obtain the area.
 Therefore, the answer is: 
