Atailor used 2 meters of string to make 10 halloween masks. he used of a meter for each mask

The answer is 20 millimeters because there is 100 millimeters and to make 10 masks 20 millimeters times 5 is 1 meters and 5 masks 

Well if you have 20 bats you probably want 20 balls? you don’t have enough context to answer the question.