to determine wether the system has one solution, an infinite number of solutions or no solution at all we have to solve it.
We have the system:
Substracting the second equation from the first one we have:
Since we can find a value for the variable y we conclude that the system has only one solution.
The value of x can be found from the first equation once we have y:
The solution of the sytem is x=40 and y=11/3.