Ayuda plis doy puntosss y corona

Which expression can be used to determine the slope of the line that passes through the points -6, three and one, -9

∆red ≅ ∆ by rule will give brainiest if possible

Sue's average score for three bowling games was 162. in the second game, sue scored 10 less than in the first game. in the third game, she scored 13 less than in the second game. what was her score in the first game?