Answer:
41cm
Explanation:
If observed closely you can see that perimeter C is the merged factor of both perimeter A and B.
To get the perimeter of C, merge both perimeter A and B together
The height will be 10cm
The bottom will be 6cm seeing as the top of perimeter A is 6cm and there are the same length
The top will be 6+7 = 13cm because perimeter A and B have been merged meaning they will be added
The right side will be 5cm because 5cm is the side of perimeter B
The long bottom will be 7cm because it is the same as perimeter B and they have the same length meaning
10+6+13+5+7 = 41cm(The answer is not squared because we only added the sides not multiplied it)