To solve this question, you have to take the 2D shape and divide it up into 6 boxes, of which you find the area of each. For easier reference, here's a picture where I've numbered the boxes.
Box 1: Nothing special here, just 25*12= 300 cm²
Box 2: The height of box 2 is obvious but the length is found from the above box. 25*18= 450 cm²
Box 3: Box 3 is the opposite of box 2, with an obvious length, but a width which is found from box 2. 12*18= 216 cm²
Box 4: Box 4 receives its height from box 2 and its length from box 6. 25*18= 450 cm²
Box 5: Box 5 has an obvious length but receives its height yet again from box 2. 12*18= 216 cm²
Box 6: Box 6's parameters are both obvious. 25*12= 300 cm²
The next step is to add the area of all the sections. 300+450+216+450+216+300= 1932 cm²
I hope this helped you!