Final answer:
The equation that represents the relationship between the number of hats and the number of scarves is h + 2h = 20.
Step-by-step explanation:
To represent the relationship between the number of hats and the number of scarves, we need to use the given information that Elliott wants to use twice as much yarn for scarves as for hats and she wants to make a total of 20 items. Let h be the number of hats Elliott makes.
The equation that represents this relationship is:
h + 2h = 20
This equation shows that the sum of the number of hats and twice the number of hats is equal to 20, which represents the total number of items Elliott wants to make.