Question

Plz help and no guessing

Answer 1

Multiply 1st equation by 5
-5x + 10y = -20

now you have
-5x + 10y = -20
 5x - 10y = 20
---------------------add
 0 + 0 = 0
0 = 0

answer
C. the system has infinitely many solutions

Answer 2

When I multiply the top equation by 5 I get the following system:
-5x + 10y = -20
5x - 10y = 20

Add them together you then get 0 = 0.  Since 0 always equals 0 then the system will have infinitely many solutions