The work of a student to solve the equation 2 (6y - 3) = 20 + 6y is shown below:

Step 1: 2 (6y - 3) = 20 + 6y

Step 2: 8y - 5 = 20 + 6y

Step 3: 2y - 5 = 20

Step 4: 2y = 25

Step 5: y = 12.5

In which step did the student first make an error and what is the correct step?

Step 2: 8y-5=10+3y

Step 2: 12y-6=20+6y

Step 3: 6y-3=2 (18+3y)

Step 3: 2 (6y-3) = 18+3y

Question

Mathematics

Jordan

6 July, 10:25

The work of a student to solve the equation 2 (6y - 3) = 20 + 6y is shown below:

Step 1: 2 (6y - 3) = 20 + 6y

Step 2: 8y - 5 = 20 + 6y

Step 3: 2y - 5 = 20

Step 4: 2y = 25

Step 5: y = 12.5

In which step did the student first make an error and what is the correct step?

Step 2: 8y-5=10+3y

Step 2: 12y-6=20+6y

Step 3: 6y-3=2 (18+3y)

Step 3: 2 (6y-3) = 18+3y

+1

Answers (1)

Know the Answer?

Frosty · Answer 1

2 (6y - 3) = 20 + 6y

Use the distributive property, which states a (b - c) = ab - ac

We should get:

2*6y - 2*3 = 20 + 6y

Which can be simplified to:

12y - 6 = 20 + 6y

That means the mistake was in step 2. The student didn't multiply the numbers and instead added the numbers.

Your answer is: Step 2: 12y-6=20+6y