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y-(-20)=1(x-(-10))

Step-by-step explanation:

If you're really in college you should know this, but here's the explanation:

m= -9-(-20)

      1-(-10)

  = 11

     11

m = 1

The equation is y-y^1=m(x-x^1)

Replace the y^1, m, and x^1 from the first point

You get y-(-20)=1(x-(-10))

Or simplify that into y+20=x+10

You can also simplify it more but I don't think you need that for that question

it would rotate about 180 degrees.