Me on this one kinda stuck on this you

1) 100 * 40 = 4000 (cm²) the area of rectangle
2) 40 * 30 * 1/2 = 600 (cm²) the area of triangle
3) 4000 + 600 = 4600 (cm²)

4600 cm²

First find the area of the rectangle like so, 100 * 40 = 4000cm
Then, find the area of the triangle like so, 30 * 40 = 1200cm
Then, since the triangle is a triangle, and not a square, you divide 1200cm by 2, and get 600cm. 
Finally, add them up. The answer you should get is 4600cm².