Answer: He used [tex]\dfrac{1}{5}[/tex] of a meter for each mask.
Step-by-step explanation:
Given : A tailor used 2 meters of string to make 10 Halloween masks.
Here, Total length of string = 2 meters
Number of masks = 10
The the part of a meter of string is used for each Halloween mask will be :-
[tex]\dfrac{2}{10}=\dfrac{1}{5} \text{ meter}[/tex] [Divide total length of string by number of masks]
Hence, he used [tex]\dfrac{1}{5}[/tex] of a meter for each mask.