The work of a student to solve a set of equations is shown below:
Equation 1: x + 2y = 10
Equation 2: 2x + 5y = 15
Step 1: –2(x + 2y) = –2(10)
2x + 5y = 15
Step 2: –2x – 4y = –10
2x + 5y = 15
Step 3: 1y = 5
Step 4: x + 2(1) = 10
Step 5: x = 8
In which step did the student first make an error? (4 points)
Step 1
Step 2
Step 3
Step 4
