You have the following system of equations:
2x - y = 7
6x - 3y = 14
In order to solve the previous system of equations you can use different methods. Here, you can use susbtitution. You proceed as follow:
solve the first equation for y:
2x - y = 7
-y = 7 - 2x
y = -7 + 2x
Next, this expression for y is replaced in the second equation:
6x - y = 7
6x - (-7 + 2x) =7
6x + 7 + 2x = 7
4x = 0
x = 0
The solution is the trivial solution, hence, the system has INFINITE SOLUTIONS