Question

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

Answer 1

The error is in Step 3.

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Simplifying 3(y +7) -2y = 8 should result in
3y +21 -2y = 8

Step 4: y +21 = 8
Step 5: y = -13