
Step-by-step explanation
to solve this divide the figure into 3 rectangles, so
Step 1
find the area of the rectangles
the area of a rectangle is given by:

then, find the areas
let
a)Rectangle 1(blue)
length=12
width=4

b)
Rectangle 2
length=12
width=3

c)
Rectangle 3
Length=5
Width=12-4-5=3

Step 2
find the total area

I hope this helps you