Answer:
126.
Explanation:
Each rectangle is a step. We'll start with the top one. This is simple: 6 times 3.
The farthest left is 5 times 3.
The crossed one is 6 times 5.
The one to the right of the crossed one is 3 times 5, again.
The farthest right is 6 times 5, again.
The bottom one is 6 times 3, again.
Now, we add.