運算式 6: "m" equals StartFraction, left parenthesis, "d" minus "b" , right parenthesis Over left parenthesis, "c" minus "a" , right parenthesis , EndFractionm=d−bc−a
6
運算式 7: "y" minus "d" equals "m" left parenthesis, "x" minus "c" , right parenthesisy−d=mx−c