Sketch in a line to divide the figure into 2 small rectangles.
The small rectangle on the top has length 4 cm and width 2 cm so its area is 4 times 2 or 8 square centimeters.
The big rectangle has width 4 cm but its length is a little trickier to find. If you add up all the little horizontal segments along the top, together they should be the same length as the whole bottom, 12 cm.
So the area of the big rectangle is 10 times 4 or 40 square cm.
Adding the area of the little rectangle to the area of the big rectangle gives a total area of 8 + 40 or 48 square cm for the whole figure.