Answer:
the three red tiles in the model represents -3x
Explanation:
From the given diagram, the three red tiles have -x, -x and -x
To find what 3 red tiles represents , we need to add all the three red tiles
Red tiles represents -x + -x + -x
Combine all the terms to add it
All terms are like terms. -x means -1x

So , the three red tiles in the model represents -3x