William solved the system of equations below. What mistake did he make in his work?
3x + y = 6
x − 2y = 2

y = 6 + 3x
x − 2(6 + 3x) = 2
x − 12 − 6x = 2
−5x − 12 = 2
+ 12 +12

x = 2.8

3(2.8) + y = 6
8.4 + y = 6
−8.4 −8.4
y = −2.4

He should have substituted 6 − 3x.

He combined like terms incorrectly. It should have been 5x instead of −5x.

He made a mistake in distributing −2.

He made no mistake.

Question

William solved the system of equations below. What mistake did he make in his work?
3x + y = 6
x − 2y = 2

y = 6 + 3x
 x − 2(6 + 3x) = 2
x − 12 − 6x = 2
−5x − 12 = 2
   + 12 +12

   x = 2.8

3(2.8) + y = 6
 8.4 + y = 6
−8.4       −8.4
          y = −2.4

 He should have substituted 6 − 3x.

 He combined like terms incorrectly. It should have been 5x instead of −5x.

 He made a mistake in distributing −2.

 He made no mistake.

anonymous · Answer

$$3x+y=6$$Implies$$y=6-3x$$Not$$y=6+3x$$Choose your answer, accordingly.