Answer:
Width: 8; Length: 10
Explanation:
Every square meter in the room is worth 90, and the room is worth 7200 total. Given this information, if we divide the total, 7200, by the value per square meter, 90, we get that there are 80 square meters in this room. We also know that the value of the second room, 3600, is half of the first room. And if subtracting 5 from the first room's length halves the value, then we know that the subtraction halved the length.
Since we now know that the Length = 10, we have a much simpler equation of 10W = 80, 10 being the length, W being the width, and 80 being the total square meters, and after a quick simplification, we have W = 8.