Ihave problems understanding systems variable like this example
4x - 2y +z =8
-y +z=4
2z= 4

4x−2y+z=8
Step 1: Add 2y to both sides        4x−2y+z+2y=8+2y4x+z=2y+8
Step 2: Add -z to both sides         4x+z+−z=2y+8+−z4x=2y−z+8
Step 3: Divide both sides by 4      4x4=2y−z+84x
=1/2y+−1/4z+2

−y+z=4
Step 1: Add -z to both sides          −y+z+−z=4+−z−y=−z+4
Step 2: Divide both sides by -1     −y−1=−z+4−1y

=z−4

2z=4
Step 1: Divide both sides by 2  2z/2=4/2
=z=2

Step-by-step explanation:

The answer is A and the car went 65 miles per hour