Final answer:
To find out how much money Trystan needs to buy the candy, subtract the amount of money her mother gave her from the total cost of the candy.
Step-by-step explanation:
To find out how much money Trystan needs to buy the candy, we need to subtract the amount of money her mother gave her from the total cost of the candy. Trystan wanted to buy $27.84 worth of candy, so we subtract the given amount from the total cost:
Total cost of candy - Amount given by mother = Amount Trystan needs
$27.84 - Amount given = Amount Trystan needs
Substituting the given amount of money from Trystan's mother, we get:
$27.84 - Amount given = $27.84 - amount given