when solving for the value x in the equation 4(x-1) +6= 18, aaron wrote the following lines on the board:
lines 1 : 4(x-1) + 6 = 18
line 2: 4(x-1)=12
lines 3: 4x-1=12
lines 4: 4x=13
lines 5: x=13/4

which property was used incorrectly when going from line 2 to line 3