Let´s represent the problem's variables by the following letters:
X : PACKAGES OF CRACKERS
Y: PACKAGES OF COOKIES
Z : CANDY BARS
Then we have the following linear system
First linear equation: A snack bag containing 6 of each type of snack costs $21.00.
6X + 6Y + 6 Z = 21
Second linear equation: . A snack bag containing 8 packages of crackers, 5 packages of cookies, and 10 candy bars costs $26.00
8X + 5Y + 10 Z = 26
THIRD LINEAR EQUATION: A snack bag containing 5 packages of crackers, 4 packages of cookies, and 7 candy bars costs $18.50.
5X + 4Y + 7Z = 18.50
So the system of equations that can be used to determine the price of each snack is:
6X + 6Y + 6 Z = 21
8X + 5Y + 10 Z = 26
5X + 4Y + 7Z = 18.50