Answer: 96 cm
Explanation:
The perimeter is the combined sum of the sides.
So 18 + 22 + 3 + 8 + 6 + 15 = 72
To find the 2 missing sides we use the information we already have.
On the top, we can see 18 is overall the largest line from the missing side.
So we'll need to subtract something from 18.
15 - 8 = 7 ( Inferencing )
18 - 7 = 11 ( length of the top missing side )
22 - 9 = 13
11 + 13 + 72 = 96 cm