Question

Read the following prompt and type your response in the space provided.

Kim's teacher has marked this problem as one to recheck, but Kim cannot determine what she has done incorrectly. Identify Kim's error and write a correct solution.



Six less than 2 times a number is 50. What is the number?

2x – 6 = 50 (line 1)

2x – 6 – 6 = 50 – 6 (line 2)

2x = 44 (line 3)

2x ÷ 2 = 44 ÷ 2 (line 4)

x = 22 (line 5)

Answer 1

Kim’s error was in line 2 when she subtracted 6 instead of adding it. To cancel out -6, you would have to ADD 6, not subtract. So doing what Kim did would actually just make the problem 2x - 12 = 44, not have gotten rid of the -6.
If Kim had added 6 instead, she would’ve gotten
2x - 6 + 6 = 50 + 6 in line 2
2x = 56 in line 3
2x / 2 = 56 / 2 in line 4
x = 28 in line 5