I have already completed the question but I am confused on how I got the the answer.

y−y1 = m(x−x1)

y−2 =

-1

3

•(x−1)

y−2 =

-1

3

x+

1

3

y−2 =

-1

3

•(x−1)

y−2 =

-1

3

x+

1

3

1

3

x+y =

7

3

3

x+y =

7

3

3•

1

3

x+3•y = 3•

7

3

7

3

x+3y = 7

How did I get the 7?

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