Given: A local shop sold 320 cheeseburgers and hamburgers combined
To Determine: The number of hamburgers sold if the number of cheeseburgers sold was three times the number of hamburgers
Solution
Let x represents the number of cheeseburgers sold and y be the number of hamburgers sold
Therefore
Also, the number of cheeseburgers sold was three times the number of hamburgers
Let us combine the two equations
Substitute the y into equation 1
Hence, the number of hamburger sold is 80