Answer:
This system has no solution.
Explanation:
The equation y=2x+3 has already been solved for y, so we can substitute (2x+3) for y in the other equation, 2x - y = 7: 2x - (2x + 3) = 7. But note that simplifying this last result turns out -3 = 7, which is of course impossible. Thus, this equation has no solution.