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

In which step did Ernesto make the first error?

Step 3: 3y + 7 – 2y = 8

Step-by-step explanation:

x – y = 7         x = y+7

3x – 2y = 8

Substitute into the second equation

3(x+7) -2y = 8

Distribute

3x+21 -2y = 8    Step 3: 3y + 7 – 2y = 8

Step3  has an error.  He did not distribute correctly

correct answers below:

3; 9 is 8 to -4

step-by-step explanation: