What is the mistake below?
Solve the system equations by substitution:
4z y = 20
-2x - 2y = 10
Step 1: Rearrange the first equation for y since the y variable has a coefficient of 1.
4x - y = 20
-y=-4x+20
y = 4x-20
Step 2: Substitute 4x-20 in for y in the second equation.
-2x - 2y = 10
-2x-(4x-20) = 10
-2x-4x+ 20 = 10
-6x = -10
x = 5/3
Step 3: Plug 5/3 in for x in either equation to get y
The error is in

A. Step 1. 4x should have been added to both sides

B. Step 1: It should be y= -4x-20.

C. Step 2: The negative is only being distributed to the 4x

D. Step 2: (4x-20) should be multiplied by -2 since it was -2y and (4x-20) only replaces the y.

E. Step 3. The x value can only be plugged into the second equation