A building with a scale of 1:100 is 60 cm in length and 4:1 in width. What is the actual building area of this building What's the formula

A building with a scale of 1:100 is 60 cm in length and 4:1 in width. What is the actual building area of this building What's the formula

Practical questions?
1. Width: 60 divided by 4 = 15 cm
2. Actual length: 60 × 100 = 6000 cm = 60 m
3. Actual width: 15 × 100 = 1500 cm = 15 m
4. Actual building area: 60 × 15 = 900 square meters