Respuesta :

number 1 is the answer
//It's been while doing this, not sure it's right.

2R1 means multiplying row 1 by 2
[1 -5] *2. ----> [2 -10]

Now add R2 to R1:
[2 -10] + [0 4] -----> [2 -6]

Answer: A
[2 -6]
[0 4]

//Again not sure, but make sense. Hope this helps