Answer:
Option C
The student's conclusion is correct because the solution to the system of equations 
 and 
 is 

Explanation:
Let
x------> the cost of each burger
y-----> the cost of each sandwich
we know that
 -----> equation A
 
 ----> equation B
Solve the system of equations
Multiply the equation B by 

 ----->
 ------> equation C
Adds equation A and equation C

Substitute the value of x in the equation B



The solution of the system of equations is the point 

so
The price of each burger is 

The price of each sandwich is 
