Answer:
System 1 has an infinite number of solutions and System 11 has no solution.
Explanation:
System 1:
x = y - 3
x - y = -3
2x - 2y = -6
Divide above by 2:
x - y = -3
So the 2 equations are identical
and they have an infinite number of solutions.
System 11:
5x + 2y = -7
15x + 6y = 21
Divide the above by 3:
5x + 2y = 7
Comparing this to the first equation the left sides are the same but right sides are different ( -7 and 7)/
There is no solution to this system.