Answer:
375 hamburgers
Explanation:
The variables are the number of hamburgers and the number of cheeseburgers.
Let x represent the number of hamburgers sold on Monday and y represent the number of cheeseburgers sold on Monday.
Therefore:
x+y=816 (I)
The number of cheeseburgers is the number of hamburgers plus 66:
y=x+66 (II)
You have to solve the system of equation using a solving method, for example substitution:
Replacing (II) in (I) and solving for x:
x+x+66=816
2x+66=816
Subtracting 66 both sides:
2x=816-66
2x=750
Dividing both sides by 2:
x=375
Replacing the value of x in (II):
y=375+66
y=441