Given:
Width = x
Length = x + 3
To find:
Which model and solution is correct for the given situation.
Solution:
Sum of the length and width of a rectangle is more than 15 units.
⇒ width + length > 15
--------------- (1)
This model represents the situation.
Adding x:

Subtract 3 on both sides.


Divide by 2 on both sides.

--------------- (2)
The correct model and solution is represents the situation is
.