finding a equation in slope-intercept form. Through (-9, 2.5) and (-5, 4.5)

Answer 1

Y= -1/7X + 1.2

Answer 2

(Y2-Y1)/(X2-X1) = slope

(4.5-2.5) / (-5+9) = slope call it m
then
(y-Y1)/(x-X1) = that same slope, m
so finally

y = Y1 + m (x-X1)

Answer 3

Is this correct? Ans. y=2x+20.5