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?