The work of a student to solve a set of equations is shown:

Question

Equation A: y = 15 − 2z
Equation B: 2y = 3 − 4z

Step 1: −2(y) = −2(15 − 2z) [Equation A is multiplied by −2.]
2y = 3 − 4z [Equation B]
Step 2: −2y = 15 − 2z [Equation A in Step 1 is simplified.]
2y = 3 − 4z [Equation B]
Step 3: 0 = 18 − 6z [Equations in Step 2 are added.]
Step 4: 6z = 18
Step 5: z = 3
In which step did the student first make an error? (5 points)

Step1

Step 2

Step 3

Step 4

Answer 1

The student first made an error in **Step 3**. When adding the two equations together, the correct result should be 0 = 18 - 6z, not 0 = 18 - 6z. This error led to incorrect subsequent steps.