Answer:
38 m²
Step-by-step explanation:
You want the area of a 5 m by 8 m wall, not including a 2 m by 1 m doorway.
The area of a rectangle is the product of its length and width:
A = LW
A = (5 m)(8 m) = 40 m² . . . . . . area of wall including doorway
The doorway area is figured the same way:
A = LW
A = (2 m)(1 m) = 2 m²
We want the net area of the wall without the doorway included, so that is ...
wall area - doorway area = (40 m²) -(2 m²) = 38 m²
The area Father will paint is 38 square meters.