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
[tex]x+y=320[/tex]Also, the number of cheeseburgers sold was three times the number of hamburgers
[tex]x=3y[/tex]Let us combine the two equations
[tex]\begin{gathered} equation1:x+y=320 \\ equation2:x=3y \\ Substitute,x=3y,into,equation1 \end{gathered}[/tex][tex]\begin{gathered} 3y+y=320 \\ 4y=320 \\ \frac{4y}{4}=\frac{320}{4} \\ y=80 \end{gathered}[/tex]Substitute the y into equation 1
[tex]\begin{gathered} x=3y \\ x=3(80) \\ x=240 \end{gathered}[/tex]Hence, the number of hamburger sold is 80