Expression 20: "y" equals "m" Subscript, 1 , Baseline left parenthesis, "x" minus "B" Subscript, 1 , Baseline , right parenthesis plus "B" Subscript, 2 , Baseliney=m1x−B1+B2
20
Expression 21: "y" equals negative 1 left parenthesis, "x" minus "O" Subscript, 1 , Baseline , right parenthesis plus "B" Subscript, 2 , Baseliney=−1x−O1+B2
21
Expression 22: "m" Subscript, 1 , Baseline left parenthesis, "x" minus "B" Subscript, 1 , Baseline , right parenthesis equals negative 1 left parenthesis, "x" minus "O" Subscript, 1 , Baseline , right parenthesism1x−B1=−1x−O1