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