Ernesto tried to determine the solution for the system of equations using substitution. His work is shown below.x – y = 73x – 2y = 8Step 1: x = y + 7Step 2: 3(y + 7) – 2y = 8Step 3: 3y + 7 – 2y = 8Step 4: y + 7 = 8Step 5: y = 1

Step 1 correctly rewrites x − y = 7 as x = y + 7, and Step 2 substitutes that expression for x. In Step 3, Ernesto distributes 3 incorrectly: 3(y + 7) should equal 3y + 21, not 3y + 7. Therefore, the error is Step 3.

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