Answer: The width of each flag = 12 cm
The average amount of time it takes Sandra to make each flag = 20 minutes.
Explanation:
Given: The ratio of the length to the width the official german flag is 5:3.
Let length = 5x, width = 3x
Length of each flag = 20 cm
i.e.

Then width of each flag = 3 x 4 = 12 cm
i.e. width of each flag = 12 cm
Total time to make 12 flags = 4 hours
Time taken to make 1 flag =
hour
Time taken to make 1 flag =
hour
1 hour = 60 minutes
Time taken to make 1 flag =
minutes = 20 minutes.
Hence, the average amount of time it takes Sandra to make each flag = 20 minutes.