Answer:
78 cm^2
Explanation:
This will require 3 steps.
1) Area of the entire rectangle
18cm * 8 cm = 144 cm^2
2) Area of the square with one side length of 9cm
The missing measurement for the heights below 2cm
8cm - 2 cm = 6 cm
This area will be 6cm * 9 cm = 54 cm^2
3) Triangle
You have your height, which is 6cm
You also have your base, 18 cm total length minus the 5 cm stated minus the 9 cm also stated.
18cm - 5cm - 9 cm = 4 cm
The area of a triangle is A= h b/2
A = 6 * (4/2)
A = 12 cm^2
Now substract the sum of the smaller rectangle and the triangle from your large triangle
144 - 54 - 12