Respuesta :
Given:
The cost of a hamburgers, h=$2.0.
The cost of a cheeseburgers, c=$2.50.
The total number of burgers sold, n=17.
The amount made by Sam by selling burgers, A=$39.
Let x be the number of hamburgers sold and y be the number of cheeseburgers sold.
The expression for the number of burgers is,
[tex]\begin{gathered} n=x+y \\ 17=x+y------(1) \end{gathered}[/tex]The expression for the amount made by Sam by selling burgers is,
[tex]\begin{gathered} A=hx+cy \\ 39=2x+2.5y-----(2) \end{gathered}[/tex]Multiply equation (1) by 2.
[tex]34=2x+2y\text{ -------(3)}[/tex]Subtract equation (3) from (2) to obtain the value of y.
[tex]\begin{gathered} 39-34=2.5y-2y \\ 5=0.5y \\ \frac{5}{0.5}=y \\ 10=y \end{gathered}[/tex]Therefore, the number of cheese burgers sold by Sam is 10.
