For this case, we propose a system of two equations with two unknowns.
Let:
x: The variable that represents the number of biscuit boxes sold by Tori Chang
y: The variable that represents the number of biscuit boxes sold by Kai Chang
Between the two they sold 110 boxes of cookies:
If Kai sold 4 times more boxes of cookies than Tori we have:
We substitute the second equation in the first:
Then, Tori Chang sold 22 boxes of cookies.
Kai Chang sold 88 boxes of cookies.
Answer:
Tori Chang: 22 Boxes
Kai Chang: 88 boxes