Answer: 141 hamburgers were sold on Tuesday.
Explanation:
Let x represent the number of hamburgers that were sold on Tuesday.
Let y represent the number of cheeseburgers that were sold on Tuesday.
On Tuesday, a local hamburger shop sold a combined total of 564 hamburgers and cheeseburgers. It means that
x + y = 564- - - - - - - - - - -1
The number of cheeseburgers sold was three times the number of hamburgers sold. It means that
y = 3x
Substituting y = 3x into equation 1, it becomes
x + 3x = 564
4x = 564
x = 564/4
x = 141
y = 3x = 3 × 141
y = 423