To solve this question, follow the steps below.
Step 01: Find the real measures of the bedroom.
Given the measure in the drawing: 8 cm x 12 cm.
Given the scale: 4 cm = 5 m.
We can use proportion to find the real measures.
First side:

Multiplying both sides by x*5m

Diving both sides by 4cm:

Second side:
Doing the same steps for the second side:

The measures of the real bedroom are 10m x 15m.
Step 02: Find the area of the bedroom.
The area (A) of the bedroom is the area of a rectangle and can be found by multiplying the sides.

Answer: The area of the real bedroom is 150 m².