Answer: The dimensions of the builder's scale drawing is 40 x 32 inches.
Explanation:
The scale factor of Karl = 1:12
Dimensions = 10 x 8 inches
Area = 80 square inches
1:12 = 1/12
1/12 = 80/a
a = 80 x 12
a = 960 square inches
So dimensions are 120 x 96 inches
Builders scale factor = 1:3
Actual Length = 120inches
Actual width = 96 inches
Builders drawing length = 120/3
= 40 inches
Builders drawing width = 96/3
= 32 inches